Re: [ntp:questions] questions] questions] Ntpq.exe memory issue with windows 2019
From: juergen perlinger [] If running NTP, Windows Time Service should be disabled anyway. !!! s/should/MUST/ !!! 1.) two services competing for port 123/UDP is a bad idea. 2.) Two services trying to adjust the clock is an even worse idea! = Yes, indeed! This was "should" in the sense that "You should have found it in a disabled state, if not, something is wrong.". I had wondered whether they were using ntpq against the Windows Time Service. David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Ntpq.exe memory issue with windows 2019
Hi, Yes The issue goes away if I disable the execution of ntpq.exe, Please check the link I have shared in my earlier comment. I'm tracking the problem down and so far I have found that the issue doesn't occur if you have the windows time service disabled. === If running NTP, Windows Time Service should be disabled anyway. David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Ntpq.exe memory issue with windows 2019
Thanks for your report. On a newly installed PC running Windows-10 Pro, using standard NTP I see a loss of "Available" memory of about 16 kB per ntpq invocation. Numbers: running ntpq in a Perl script. This Perl script is called (with different parameters) four times for each node. I'm monitoring ~25 nodes, so that's about 100 calls for each MRTG check, which is every five minutes, making 28,800 calls per day. Loss (by visual inspection) is 8 GB in 17 days. So approximately 16 kB per ntpq invocation. From other monitoring, ntpd is completely constant in memory usage (35-40 MB). I'll see whether entering an NTP bug still worksit does so I'll add evidence to your 3695. == Update - no stray ntpq.exe processes showing here in the RAMMAP page table. Perhaps the memory usage here is just cached data until the memory starts to run out? https://www.satsignal.eu/mrtg/performance_penguin.php Looks like the pattern changed from ~23:00 last night. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Ntpq.exe memory issue with windows 2019
-Original Message- From: Sadique Urf Arbaz Sayyed We started with a brand new windows server 2019 datacenter edition and installed an infrastructure monitoring agent on it and strictly no other program. The machine had 8 GB of memory. As part of monitoring NTP offset from sync'd host we scheduled a ntpqexe. The problem started after 4-5 days, the memory utilisation had increased to significant level >80%. On analysis we found it was a gradual increase and using RAMMAP we saw every time the ntpq.exe will run it will leave behind 24k of memory in PAGE Table with 0 B in Private. Moreover this issue is specific to windows server 2019 we tried following same steps on windows server 2012 machine and it worked perfectly fine with no memory creeping issues. Any help or pointer are appreciated = Thanks for your report. On a newly installed PC running Windows-10 Pro, using standard NTP I see a loss of "Available" memory of about 16 kB per ntpq invocation. Numbers: running ntpq in a Perl script. This Perl script is called (with different parameters) four times for each node. I'm monitoring ~25 nodes, so that's about 100 calls for each MRTG check, which is every five minutes, making 28,800 calls per day. Loss (by visual inspection) is 8 GB in 17 days. So approximately 16 kB per ntpq invocation. From other monitoring, ntpd is completely constant in memory usage (35-40 MB). I'll see whether entering an NTP bug still worksit does so I'll add evidence to your 3695. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Realistic Performance Expectation for GPS PPS fed ntpd jitter
Hello, I wonder what's a realistic ballpark for the jitter I can expect when feeding a GPS PPS into ntpd? [] Thanks, regards Andreas === Andreas, I have some offset plots here: https://www.satsignal.eu/mrtg/performance_ntp.php and a few experimental clock and system jitter plots here: https://www.satsignal.eu/mrtg/performance_ntp_jitter.php For an unloaded Raspberry Pi, 1-4 us, for an RPi carrying out another task perhaps as high as 5-7 us for an RPi zero. For a Windows-10 PC 4-50 us depending on load and CPU speed and age. All given a reasonably clear satellite view, and no GPS jammer truck parked outside! [us => microsecond] Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Local Time NTP Server
Why? Repetition? Is PST time also annoying? Universal Time Coordinate time is not really repetitious anyway, since the noun is Coordinate. And UTC time means the type of time defined by UTC-- since there are lots of other types of time one could use-- including decimal time ( 100 sec/min/ 100min/hr, 10hr/day) Yes, Time Time (UTC time) is as annoying as Number Number (PIN number). The noun is "T", "U" and "C" adjectives. In the UK, we would never say "GMT time" or "BST time". Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] [HINT]: NTP server installation
Hi Team, I am new to NTP . I want to estimate my machines configurtion that can be good enough to run NTP server and give time to the network nodes. 1.Is NTP package comes with Ubuntu 14 version or I only need to install it from internet. 2. Basically I do not have internet connction on my linux machine can some package offline can be used for ntp Thanks David caul == David, 1. Likely the supplied package will be good enough. NTP isn't a major load - even a Raspberry Pi can handle hundreds of clients (if not more). 2. You can use a GPS device both to get the time of day, and the edge of the second. If sync to UTC isn't required, NTP can work in a stand-alone mode, but I have no experience of that. A Raspberry Pi card, GPS expansion, and GPS puck could be all you need: https://ava.upuaut.net/?p=951 Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Performance estimation
From: Dan Drown The system's time (kernel "clocksource") on the RPI is actually not running at the same speed as the CPU clock. From dmesg: arch_timer: cp15 timer(s) running at 19.20MHz (phys). This gives you around 52ns of resolution. I believe it's the same on all the rpi models. I would also like to see whether the characteristics of the GPS and its location make a measurable difference to the RPi's timekeeping. For example: is it better to have a GPS with 3 service capability at a location where the signal is poor, or is it masked by the RPi's performance? All this with kernel-mode PPS. What I've used for this is a percentile of offsets. Looking at the 1% and 99% values on a histogram is an estimate of the system's stability. For instance (not an rpi): https://dan.drown.org/cheese/run3/offset-histogram.png So from that graph, I can say that 98% of the time, the system clock is within +/-80ns of the PPS. I believe you're using ntpd, and my code to generate that graph from ntpd logs is here: https://github.com/ddrown/chrony-graph/tree/ntpd Quoting William Unruh: The question then is how rapidly the system can respond to an interrupt,. This at least used to be of the order of a microsecond. Also, how logd does it take to read the clock with the kernel gettime routines. They all limit the accuracy of your clock using gps refclock (and also how long the wire is between the gps unit and the computer) On different ARM hardware (beaglebone black), I've measured interrupt latency: https://blog.dan.drown.org/content/images/2014/Dec/interrupt-latency.png I'd expect the rpi to have a similar magnitude. Somewhere around +10us delay and 1us jitter. = Dan, Thanks for the info on the RPi system clock. Even at 19 MHz, it's way better than the microsecond level in part of the ntpq -crv report. I've now discovered that at least one item there is at nanosecond level, so I've updated the Perl script and MRTG presentation accordingly. I also prefer plotting offsets, and I have a Windows program which allows histogram plots. Just checking the histogram on a couple of Windows PCs they show mean 0.2 & 0.3 us and SD 7 and 10 us. I don't know what the path is on the RPi for the PPS interrupt but I would expect it to be similar to that on the BBblack, so that latency graph is of interest - thanks! Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Time syncing with something other than ntpd
There is a Garmin GPS 18x High-Sensitivity LVC Sensor 010-00321-36 for sale on eBay here: http://www.ebay.com/itm/Garmin-GPS-18x-High-Sensitivity-LVC-Sensor-010-00321 -36-/77215324?hash=item33c0c1245c:g:L-gAAOSwOyJX-6Dn&vxp=mtr for only $45.86 USD, $59.99 C in Canada. I bought one from eBay for $39 not too long ago, so all you really have to do is look. The Sure device works, but for me it was too difficult to make the PPS work. I bought two and was unable to make either one output a detectable PPS. The PPS was there, my scope told me so, but I could not make the computer detect it. On the other hand, I am very clumsy, and have little experience with electronics. Charles Elliott = Thanks for that, Charles, good to know they are still around, and at a good price. A pity about the Sure device as I had no problems and now use one Sure device to feed two PCs (ground, PPS and RX-input-to-PC connected on one PC, TX-from-PC as well on another). I have seen PCs not detect a 0/3.3V level RS-232 signal (it's too little voltage, should be at least +/- 3V) on the RX/TX lines, and yet strangely they can see the 3.3V DCD signal! The mod I showed for the Sure board should give a full-level RS-232 signal, though, which should easily be seen by the PC. Ho, hum, one of those things. The Garmin delivers nearer to 0/5V, IIRC. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] MSF Anthorn, UK down
It is there: http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-outages Greetings, = .. and about time, too! Thanks, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Automatic time synchronization of local hw clock.
Op 15 apr. 2014, om 08:32 heeft David Taylor het volgende geschreven: On 15/04/2014 07:24, William Unruh wrote: [] No, I meant that Windows at least did (pre Win7?) use local time as system time. And I seem to recall that even now it can use localtime as systemtime. But I do not run Windows so cannot test anything. This is what I had to deal with, so a standard installation of Windows certainly does not use UTC: http://lifehacker.com/5742148/fix-windows-clock-issues-when-dual-booting-with-os-x= = I was waiting for your question to appear on the NNTP newsgroup, but it did not, at least on my server. Windows NT and later use UTC internally, which is what I wrote. You are quite correct that the BIOS time is usually in wall-clock time, and that different operating systems will handle that problem differently. There have been reports that Windows can use a BIOS clock in UTC, but I've never tried that myself. I don't know whether OS-X has the option to use wall-clock time for the BIOS - it would be helpful if it did! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Cross-compiling NTP for the Raspberry Pi
From: Charles Swiger Yes, you need to add --with-yielding_select=yes. (Or no, depending on what select() does on the target platform.) ./configure normally runs a set of tests to figure all of this stuff out, but those tests need to run on the target and not on the build platform when cross-compiling. If you don't already know the right answers, run ./configure on the target platform and use those results when cross-compiling from a faster platform. Regards, -Chuck Just what I needed to know, Chuck. Running .\configure on the Raspberry Pi, and saving the output shows three separate lines saying: checking if select yields when using pthreads... yes so I guess I need "yes". Quite why configure needs to check this three times, on an already very slow RPi PC, is a mystery! [sorry for non-standard quoting] Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] WinNT Port Performance Counter Stability and Drift
From: Charles Elliott Cc: questions@lists.ntp.org The result of reading the timestamp counter can vary wildly due to EIST (speed step technology), turbo modes, and owner overclocking, in addition to differences in CPUs, as noted. There is quite a bit about this on the Internet. As I recall, most writers recommend not using it, but if one must, using it only for short interval timing and after repeatedly measuring the frequency of the counter. The latter can take quite a bit of time, as it should be done several times, and for different interval lengths, and taking the average or median of the results. Most authors recommend using QueryPerformanceCounter and QueryPerformanceFreq if it can be determined that these functions are tied to the High Performance Event Timer (HPET), which they are on most modern systems. I believe that code to do this is already in NTPD. You can tell this from the messages in the Event Log (on Windows) when NTPD starts up. NTPD chooses the timer whose frequency is that of the HPET. Charles Elliott == Charles, and mail list admins - just to let you know that your message did not appear to reach the newsgroup: comp.protocols.time.ntp at least on my feed from Eternal-September. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] GPS/PPS and "enable calibrate"
Sorry for top posting, but Outlook is quoting things correctly. I did check out your site and based my original setup on it. Lots of impressive stuff there! The part I couldn't figure out the fudge time2 values. Using the one that was pointed out to me by Wolfgang is working very nicely with the other image. I am curious how that value is determined. I am assuming someone that understood it used the calibrate capability to come up with the 0.496 number that works for rpi-gpio cases. == Bob, I'm replying by e-mail as I haven't seen your reply appear on the Usenet server - so far. Providing your serial data is with, say, 0.5 seconds of true PPS, there's likely no need to do anything, especially if you have other servers which can provide you with the nearest second. Otherwise, the calibration steps basically are (as I understand it): - set the time fudge to zero, but the serial device to noselect. - run NTP as normal, either with Internet servers, local servers, or the PPS source as the servers. You can simply use all three, if you like. - after some time, perhaps a few minutes is enough, watch the reported offset values for the serial source. You should see that it never has a tally code in the ntpq -pn output, as it's marked noselect. - alter the time1 fudge factor (in seconds) to match the negative value of reported offset (which is in milliseconds). So if the offset is -353.00, set the fudge to +0.353. Likely you will see the offset vary perhaps by as much as tens of milliseconds, so guess (or measure) an average value. - restart NTP, and see that the reported offset for the serial data is now near to zero (within a hundred milliseconds either way is fine). - repeat and refine the offset value if you feel it is necessary. I see you mention time2. As far as I can see, time2 for the type 20 driver serves the same function as time1 for the type 28 (SHM) driver, which is what I did the tests on for the data I mentioned above. In principle, you could also use a 'scope to determine the offset, but I don't know whether you would time the start of the serial data, the end of the serial data, or the end of the first sentence of the serial data as it may differ across different implementations. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Bug 2314, Clock jitter reads zero in the loopstats file
I checked my home FreeBSD 8.2 NTP server for the clk_jitter reads zero bug, and yes, I see it too when using PPS kernel discipline. server 127.127.22.1 flag3 1 http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver22.html So, I need to understand what "Controls the kernel PPS discipline" means and what the differences in code are between disabled, (default), and enabled are. I also need to understand the importance of the clock jitter statistic; I notice that system jitter is still reported with kernel PPS discipline enabled. If system jitter is less --yet to be determined--with kernel PPS discipline enabled, wouldn't that imply that kernel PPS would be prefered, regardless of reported clock jitter? Again, I have been mostly concerned with the clock offset and the stability of the frequency. I need to understand the importance and differences in both clock jitter and system jitter? Regards, Ed == More later, but could you please add your comments to bug 2314. https://support.ntp.org/bugs/show_bug.cgi?id=2314 Thanks, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Timing issue with Linux and kernel PPS?
David, running RPi with GPS+PPS here. I compiled my own kernel and the one major gotcha I had was an RTFM issue. The kernel used on the RPi is not the compressed vmlinuz kernel used on PC's. I recompiled my kernel 10 times or more before I went back scouring the 'net to find out the kernel in use was the kernel.img file. Reason I say this is the first time I thought I had this working I was seeing kernel generated PPS signals and not GPS generated PPS signals. Life got much easier when I figured that out :) Having said all that this is what I see in my syslog when my system restarts, my GPS has battery backup so it's not a cold start on it when I reboot my RPi. Nov 15 19:17:41 pisces kernel: [ 102.192261] pps_core: LinuxPPS API ver. 1 registered Nov 15 19:17:41 pisces kernel: [ 102.192269] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti Nov 15 19:17:41 pisces kernel: [ 102.195682] pps_core: source pps-gpio.-1 got cdev (251:0) Nov 15 19:17:41 pisces kernel: [ 102.195702] pps pps0: new PPS source pps-gpio.-1 Nov 15 19:17:41 pisces kernel: [ 102.195745] pps pps0: Registered IRQ 194 as PPS source Nov 15 19:17:41 pisces kernel: [ 102.470452] pps pps0: PPS event at 1353035851.050598985 Nov 15 19:17:41 pisces kernel: [ 102.470479] pps pps0: capture assert seq #1 my /etc/modules consists of: loop pps_gpio my /etc/ntp.conf consists of: # NEMA data on /dev/gps0 server 127.127.20.0 mode 48 minpoll 3 iburst prefer fudge 127.127.20.0 flag1 0 time2 0.400 #PPS on /dev/pps0 server 127.127.22.0 minpoll 4 maxpoll 4 fudge 127.127.22.0 flag3 1 flag4 1 /dev: crw-rw---T 1 root dialout 204, 64 Nov 19 17:46 /dev/ttyAMA0 lrwxrwxrwx 1 root root 7 Dec 31 1969 /dev/gps0 -> ttyAMA0 crwxrwxrwt 1 root tty 251, 0 Nov 15 19:17 /dev/pps0 lrwxrwxrwx 1 root root 4 Nov 15 19:17 /dev/gpspps0 -> pps0 and this is what I am seeing in ntp: ntpq -c lpeers remote refid st t when poll reach delay offset jitter == *GPS_NMEA(0) .GPS.0 l18 3770.000 -55.452 9.778 oPPS(0) .PPS.0 l8 16 377 0.000 -0.001 0.001 +69.85.88.32 128.4.1.12 u 26 64 377 101.895 4.132 1.447 -irc.indoforum.o 64.147.116.229 2 u 37 64 377 18.260 4.336 2.875 -ntp1.ResComp.Be 128.32.206.55 3 u 51 64 377 38.9926.287 2.307 +199.241.31.96 164.244.221.197 2 u7 64 377 70.261 -21.524 3.039 I don't see any problems with the RPi creating the /dev/pps0 device on startup and since I've done more RTFM I actually get good PPS data :) I did contribute to the thread listed at the RPi forums but need to go back and add what got it working for me. I also moved to a more current kernel. I compiled a bunch of extra stuff in there as I want to play with the networking stuff too so my kernel is not a small one. uname -a Linux pisces 3.6.1+ #1 Fri Nov 2 02:10:35 PDT 2012 armv6l GNU/Linux James = James, Many thanks for that. Treating me as a beginner in Linux, could you perhaps give step-by-step instructions for recompiling the kernel (together with an indication of the time it may take) as I feel sure I will need to do this at some time? I take it that there is just the single PPS/GPIO code so that you are also working with pin 24? Just maybe the newer kernel doesn't have this same delayed start-up issue. I would like to add statistics gathering, but I don't want the files to accumulate and I'm unsure about how to create a scheduled task which would delete statistics file more than, say, 30 days old. Another gap in my Linux knowledge, I'm afraid! I'm suspect that CRON come into it, though. Many thanks, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Clock time synchronization of four computers
"Nazmul Islam" wrote in message news:caftrfezn5mhq_bodeg5kz7l2kga5s6ngsmfbhyksmxxm9gf...@mail.gmail.com... Hello, I have not used ntp processing before. I apologize in advance if my questions seem too novice. I am trying to synchronize the clocks of four computers. The timing does not have to be accurate but they have to be sync'd with each other. An error tolerance of 10-20 ms is acceptable. The computers are connected to the servers. = In addition to Paul Kennedy's suggestion, you can make one or two computers stratum 1 servers by adding a low-cost GPS device. These have serial RS-232 output which can be parallel connected to two PCs (on the PC's data input and DCD lines), making two of the 4 PCs stratum-1 servers. You can peer the two PCs with each other, and make these two PCs servers for the remaining two. With a simple line driver you could likely connect all four PCs to the GPS source. All PCs should also retain several Internet servers for backup. I have descriptions of a couple of low-cost GPS devices on my Web site: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Sure-GPS.htm The performance I get (using Windows) is shown here: http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
For maximum eventlog/syslog/ntp.log verbosity: logconfig =clockall +peerall +syncall +sysall If you're using recent 4.2.7 and don't expect to ever use older versions, you can abbreviate: logconfig =allall The default without logconfig is: logconfig =syncall Cheers, Dave Hart = Thanks for that, Dave. Yes, all my NTP are 4.2.7, so the abbreviated form will be fine. I've saved a note for when we might next need it. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
"Dave Hart" wrote in message news:CAMbSiYAqZsDnuNtcyYGn1XU0JBcK4DB3DHUVnsOiJy6hop6w=w...@mail.gmail.com... On Tue, Jul 3, 2012 at 06:20 UTC, David J Taylor wrote: Presumably, Dave, if the leap second /had/ been inserted, the second message would not have happened? The "would have gone backward 1 times" message was triggered by the intentional backward step, which wouldn't have occurred at the time it did if the insertion had slewed as designed. That diagnostic is supposed to be suppressed when ntpd steps the clock, but the evidence suggests imperfection. Clearing an additional variable might be all that's needed. Personally, I would correct the missing insertion, and treat the second message as a warning that /something/ unexpected had happened! I want to preserve the unexpected aspect by not logging that message when the clock is expected to step back. If the leap second /had/ been inserted, then would ntp have been confused in the period before the GPS 18/x started emitting correct seconds? It would quickly notice a 1s offset for the NMEA, which would most likely be suppressed initially as a popcorn spike. Whether the clock would be stepped to follow depends on the mix and agreement of sources. I also wonder why the 1-second step doesn't appear to have been reported in the event log. I wondered the same thing. I saw a step logged on Windows ntpd with GPS 18x LVC: 30 Jun 23:59:59 ntpd[2272]: 0.0.0.0 041b 0b leap_event 1 Jul 00:00:00 ntpd[2272]: Leap second announcement disarmed 1 Jul 00:00:15 ntpd[2272]: 0.0.0.0 0413 03 spike_detect -0.98 s 1 Jul 00:03:45 ntpd[2272]: 2001:4f8:fff7:1::17 962a 8a sys_peer 1 Jul 00:12:29 ntpd[2272]: 0.0.0.0 061c 0c clock_step -1.006282 s (followed by re-initializing interpolation spew normally seen only at startup) You may need to add "+sysall" or more narrowly "+sysevent" to logconfig in ntp.conf. Cheers, Dave Hart == Thanks , Dave. Understood about the suppression of the "would have gone backward 1 times" message, so me getting it was a [good] indicator that something was amiss. I agree with ntpd's treatment of these messages. I don't have a "logconfig" in my ntp.conf, but I could add one if reminded before any further tests. I presume the omission of these messages is part of the ntpd "say the least" approach, but I wonder whether on more critical servers (perhaps those claiming to be at stratum 1?), there should be less suppression of messages? Against that is the problem of more options meaning more support queries, and more chance of confusion for the poor user! . Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
"Dave Hart" wrote in message news:CAMbSiYByhGbjTzN8HXwuJVd_1_ez_J-HWE0BNF=ivf_e8_f...@mail.gmail.com... [] So there are at least two problems here. First the insertion is not happening, second when a 1s step occurs later, there's a "would have gone backward" that shouldn't be reported. I have an idea how to fix that part. For the first part, I'm leaning toward integrating the Windows port's leap second insertion more with the POSIX daemon loop code (while preserving the differing implementations). [] Thanks for the details, Dave Hart = Presumably, Dave, if the leap second /had/ been inserted, the second message would not have happened? Personally, I would correct the missing insertion, and treat the second message as a warning that /something/ unexpected had happened! If the leap second /had/ been inserted, then would ntp have been confused in the period before the GPS 18/x started emitting correct seconds? I also wonder why the 1-second step doesn't appear to have been reported in the event log. At least a year until we can next test this in the wild Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
Dave Hart suggested I post the following event log information about leap second behaviour on various Windows stratum-1 and stratum-2 PCs here.. ___ Stratum-1 server PC Alta (Win-7/64 + Sure GPS) (runs 24 x 7) LevelDate and TimeSourceEvent IDTask Category Warning01/07/2012 01:24:33NTP2Noneclock would have gone backward 1 times, max 1000612.1 usec Information01/07/2012 01:24:32NTP3NoneHZ 64.102 using 43 msec timer 23.256 Hz 64 deep Information01/07/2012 01:00:00NTP3NoneLeap second announcement disarmed Warning28/06/2012 00:46:08NTP2Noneclock would have gone backward 1 times, max 32.5 usec ___ Stratum-1 server PC Stamsund (Win-7/32 + GPS 18x LVC) (runs 24 x 7) LevelDate and TimeSourceEvent IDTask Category Warning01/07/2012 01:23:18NTP2Noneclock would have gone backward 1 times, max 722520.0 usec Information01/07/2012 01:21:38NTP3NoneHZ 64.000 using 43 msec timer 23.256 Hz 64 deep Information01/07/2012 01:00:00NTP3NoneLeap second announcement disarmed Warning29/06/2012 17:53:16NTP2Noneclock would have gone backward 1 times, max 10.9 usec Warning29/06/2012 05:53:16NTP2Noneclock would have gone backward 1 times, max 10.4 usec ___ Stratum-2 PC Torvik (Win-8/32) - booted especially for the event! LevelDate and TimeSourceEvent IDTask Category Information01/07/2012 01:00:00NTP3NoneInserting positive leap second. Information30/06/2012 03:55:33NTP3NoneDetected positive leap second announcement for 2012-07-01 00:00:00 UTC Information30/06/2012 03:55:31NTP3Nonepeers refreshed Information30/06/2012 03:55:31NTP3NoneListen normally on 6 Loopback Pseudo-Interface 1 127.0.0.1:123 ___ Stratum-2 PC Ystad (Win-7/32) (runs 24 x 7) LevelDate and TimeSourceEvent IDTask Category Information01/07/2012 01:00:00NTP3NoneInserting positive leap second. Information30/06/2012 01:00:13NTP3NoneDetected positive leap second announcement for 2012-07-01 00:00:00 UTC Information22/06/2012 16:09:36NTP3Nonepeers refreshed Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
From: Dave Hart Sent: Sunday, July 01, 2012 5:12 PM To: David J Taylor [] As I mentioned on the pool list, I think there's a bug in the application of the leap second to the local clock in recent ntpd. Please check the event log on each of your Windows systems around the event. If everything worked perfectly, you'd see mentions both of the positive leap second insertion occurring, and of the leap indication being disarmed. On a system with a GPS+PPS refclock, I saw only the disarming message, then a naughty -1s step 12.5 minutes later: 30 Jun 23:59:59 ntpd[2272]: 0.0.0.0 041b 0b leap_event 1 Jul 00:00:00 ntpd[2272]: Leap second announcement disarmed 1 Jul 00:00:15 ntpd[2272]: 0.0.0.0 0413 03 spike_detect -0.98 s 1 Jul 00:03:45 ntpd[2272]: 2001:4f8:fff7:1::17 962a 8a sys_peer 1 Jul 00:12:29 ntpd[2272]: 0.0.0.0 061c 0c clock_step -1.006282 s On a system synched to another NTP server, the leap second insertion (fast slew) happened but there's no message about disarming. Also both the leap_event and the insertion are relatively late: 1 Jul 00:00:33 ntpd[10184]: Inserting positive leap second. 1 Jul 00:00:57 ntpd[10184]: 0.0.0.0 061b 0b leap_event There's clearly still work to do. Cheers, Dave Hart === Yes, I saw the note, Dave, and agree with your conclusions. At least on the stratum-1 Windows systems, there is "disarmed" but not "inserted". On PC Narvik, just LAN/WAN synced, there is "inserting positive leap second" at 00:00:00 UTC, and it is reporting "leap disarmed" even though that wasn't in the event log. There was a "Detected a positive leap second announcement" at 00:00:43 UTC on June 30. I'll send you the loop & peerstats I have directly in case that helps. The PCs are running at UTC+01:00 (British Summer Time) which affects the event log timestamps. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Leapsecond on FreeBSD or Windows - no showstopper bugs, but ...
For what it's worth, I saw no showstopper bugs with either my FreeBSD or Windows systems. - The FreeBSD 8.2 fed from the Garmin GPS 18 LVC behaved perfectly. ntpd 4.2.7p255 - The Windows PCs fed from either Garmin GPS 18/x LVC or Sure Electronics GPS boards appear to have reset itself some 17..24 minutes after 00:00, suggesting they were using the GPS for the time (as well as the precise PPS edge), and the GPS devices took some time to reflect the leap-second in their serial outputs. Almanac reload time? These PCs had the leap-seconds file. Perhaps it would have been better had ntp not believed the GPS serial time for the coarse time, but the time coming from other LAN/WAN servers? This needs closer investigation. The reset resulted in a further period until normal offset accuracy was restored. ntpd 4.2.7p285. PCs: Alta, Bacchus, Feenix & Stamsund in the graphs linked below. - The Windows PCs working from LAN/WAN sources saw no glitch. ntpd 4.2.7p285 PCs: Hydra, Molde, Narvik, Torvik & Ystad in the graphs below: Offset graphs: http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Leap second preparedness
If your ntpd is relying upon other NTP servers (that is, is stratum 2 or higher), it will not announce the pending leap second starting exactly at midnight UTC in a few minutes, but should within a few polling intervals. With the default maximum interval of 1024 seconds being about 17 minutes, by 00:34 30-June UTC most systems should have picked it up that will. Cheers, Dave Hart = If it helps at all, I have a small Windows program called NTPLeapTrace. It displays the upstream leap indications contributing to a target ntpd's leap election. Although the same can be done using a series of ntpq queries, it's easier to enter a server or client name and click. Download here: http://www.satsignal.eu/software/net.htm#NTPLeapTrace I've just added a second screen-shot show the expected output under "Leap Second Today" conditions. I hope the program will be of some help. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to insert a leap second with ntpq
"Michael Tatarinov" wrote in message news:CABrG=ZyThJQchY_q90vNk=mnfwzsjeu0eocjbn0h5ovrmxu...@mail.gmail.com... Interesting program but not necessary. ntpq need only. ntpd 4.2.7 ntpq> mrv &1 &99 srcadr,leap,refid or for old ntpd ntpq> mrv 59605 59614 srcadr,leap,refid = Of course, my program is only needed for those of us who lack the ability to remember those arcane and obscure commands off the top of our heads! Double-clicking NTPLeapTrace is easier Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] questions] How to insert a leap second with ntpq
Hi again David, I ran your Leap Trace program against my gps-based time servers and not one is showing a leap second pending. Not even this one that is leap-second configured. GPSCON is showing a leap second pending on my HP Z3801. This is very mysterious. R == Ron, I believe the requirement is for the indicator only to be active (i.e. announced) 24 hours before the event. Doubtless someone will confirm or deny that. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ANN: UK GPS Jamming, Sennybridge, Wales - 2012-Sep-24 .. Oct-05
Folks, I have received the following notice: __ NOTIFICATION OF A GPS JAMMING EXERCISE SENNYBRIDGE TRAINING AREA, WALES, DURING THE PERIOD 24 SEPTEMBER - 5 OCTOBER 2012 Details of Low Power Jamming. Dates: Between 24-28 September and 1-5 October 2012 inclusive. Times: 0900 -1700 BST. Location of MULTIPLE jammers: Land based within 5km of N52° 00.881' W003° 38.518' (SN873365 - Dixie's Corner). Frequencies: 24 MHz bands centred around 1176.45 MHz (GPS L5), 1227.60MHz (GPS L2) and 1575.42MHz (GPS L1). Total Power: Up to 10 Watts EIRP. Whenever possible the transmissions will be at lower powers. Details of Higher Power Jamming. Dates: Maximum of two week-days each week between 24-28 September and 1-5 October 2012. Exact days to be notified in Jamming Warning Message circulated at least 7 days in advance of the first jamming. Times: Between 1000-1200, and 1400-1600 BST. Location of MULTIPLE jammers: Land based within 5km of N52° 00.881' W003° 38.518' (SN873365 - Dixie's Corner). Frequencies: 24 MHz bands centred around 1176.45 MHz (L5), 1227.60MHz (L2) and 1575.42MHz (L1). Total Power: Up to 100 Watts EIRP. The jamming will not affect GPS users up to a height of 25 metres AMSL around the UK coastline. Whenever possible the transmissions will be at lower powers. It is stressed that, as in previous exercises, Safety of Life operations will at all times take precedence over exercise activities. ___ Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] How to insert a leap second with ntpq
With all this discussion of leap-seconds, perhaps it's timely to mention my simple tools for leap-second checking across servers. You will find NTP Leap trace here: http://www.satsignal.eu/software/net.htm#NTPLeapTrace At this instant, fewer than 1 in 10 of the remote servers I'm using are indicating a pending leap second, and we are 9 days away from the event. I can't recall now how long before the event it should be announced by typical NTP servers. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ANN: UK MSF 60 kHz interruption, 2012 June 14
Folks, I have received the following notice: __ Notice of Interruption to MSF 60 kHz Time and Frequency Signal The MSF 60 kHz time and frequency signal broadcast from Anthorn Radio Station will be shut down over the period: 14 June 2012 from 10:00 BST until 14:00 BST The interruption to the transmission is required to allow maintenance work to be carried out in safety. __ Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Ofcom Update: UK GPS Jamming Notice
I have received the following notice: __ NOTIFICATION OF GPS JAMMING EXERCISES RAF SPADEADAM, CUMBRIA, SEPTEMBER 2012 Dates: Between the 10th of Sept to the 14th of Sept 2012 inclusive. Times: 0700 -2000 GMT. Location of MULTIPLE jammers: Land based within 5km of N55° 04.000' W002° 34.000'. Frequency: A 24 MHz band centred around 1575.42MHz (GPS L1). Total Power: Up to 10 Watts EIRP. It is stressed that, as in previous exercises, Safety of Life operations will at all times take precedence over exercise activities. NOTIFICATION OF GPS JAMMING EXERCISES SALISBURY PLAIN, WILTSHIRE, July 2012 Dates: Between the 2nd of July and the 11th of July 2012 (Weekdays only). Times: 0700 - 2000 GMT. Location of MULTIPLE jammers: Land based within 5km of N51° 12', W001° 58.5' Frequency: A 24 MHz band centred around 1575.42MHz (GPS L1). Total Power: Up to 10 Watts EIRP. It is stressed that, as in previous exercises, Safety of Life operations will at all times take precedence over exercise activities. __ Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Have Pi, have GPS = low powered NTP server?
Hi. From the title, you might (maybe) guess this is about the Raspberry Pi, and NTP. I've only had the thing a few days, but been experimenting (playing) with the default NTP behaviour as seen with ntpq -p on the command line. [] It's said, that the RasPi, has about the same cpu "grunt" as a 300MHz Pentium, but I have no way to qualify that statement. [] At present, this is all at the "it'd be good if it could be done" state. As if I don't have too many other projects on the go at this time. Comments, brickbats, bouquet's etc. Regards. Dave B (G0WBX) Dave, A small box like that would make a nice NTP server if it can be done. The only (very small) contribution I can make is that for some time I ran NTP with GPS on a Pentium 133 MHz with 48 MB of memory using FreeBSD, so you CPU-grunt is at least adequate. Rebuilding the kernel to add PPS support was an overnight job, though! [Although the two jitters of 180 milliseconds in your ntpq -p billboard is not encouraging!] Cheers, David GM8ARV ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] offline machines' time synchronization
"Dave Hart" wrote in message news:CAMbSiYBLnxaj_x4vch3eNDqwUDX+d5sGcHyr8zBe3Jh0C2K=y...@mail.gmail.com... On Thu, May 24, 2012 at 4:24 PM, Chris Albertson wrote: Lots of good discussion here but I found an easy way to stay "on-time" while the Internet is down and GPS is not available. There are some people on eBay selling Rubinium oscillators for about $40. They have a pulse per second output.These Rb clocks will keep NTP within reasonable specs for a LONG time. It does required some effort to set up. Just wanted to point out one more option. ntpd requires reference clocks provide time, not just frequency. How do you discipline the Rb PPS to occur at the top of the UTC second (or a fixed offset from the top)? Cheers, Dave Hart Agreed, Dave. The way I read the message was for /temporary/ coverage, not a fully disconnected solution. For US $40 (or somewhat more) you could easily get a secondary GPS reference such as: Trimble Resolution SMT Timing GPS OEM board eBay 290696970497 (price has gone up, though) Sure Electronics GPS evaluation board http://www.sureelectronics.net/goods.php?id=99 http://www.satsignal.eu/ntp/Sure-GPS.htm Garmin GPS 18x LVC http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html and use these to provide backup servers to cover the outage. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] New to group: radio/audio interest
I must admit I find NTP fascinating, depending on my mood. About 20 years ago I had written something that attempted to measure the drift in my computer's clock based on daily *manual* settings while listening to WWV or CHU. Room temperature was the biggest factor. I'm still interested in the audio WWV and CHU reference clocks. I don't own a GPS and I live in the boonies where the only internet connection is dialup. I'm 57, retired, partially disabled, and I like programming. I'm also a ham, but not very active. I've got a bio at http://www.qrz.com/db/ab1jx and a small homepage at http://ab1jx.webs.com. [] Alan Alan, I would suggest you get a GPS if possible. There are a number of low-cost devices now available, such as the Garmin GPS 18x LVC, and the Sure Electronics GPS Evaluation board. I've used both, and they work very well, being sensitive enough to work with an indoor antenna on the top floor of a building. The sure board is about US $35. Both require a little soldering. I've written up my experiments here: GPS 18x LVC: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm Sure board: http://www.satsignal.eu/ntp/Sure-GPS.htm Good luck with your projects! 73, David GM8ARV http://www.satsignal.eu/davids.html ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] what is refid 78.79.86.76?
Hi, i check ntp with ntpq -p and get: # ntpq -p remoterefidst t when poll reach delay offset jitter = LOCAL(0) .LOCL. 10 l 52 64 3770.000 0.000 0.001 *pluto.mydom 78.79.86.76 5 u 24 64 3770.294 0.234 0.352 What did the refid 78.79.86.76 mean? This is not the IP of the host pluto! [] TiA Bernd Try it as text - ASCII characters: NOVL It's not supposed to be anything other than a four digit set, but very often (in IPv4) it is an IP address. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Why does GPS time diverge from system time?
"Dave Hart" wrote in message news:cambsiyazzfkjmaknbc23xd4sulwtt6aggg6azxwylx14yr8...@mail.gmail.com... On Fri, Apr 13, 2012 at 19:01, Charles Elliott wrote: It's difficult when you can only hear half the conversation. Messages from "Charles Elliott" are not making it to the comp.protocols.time.ntp newsgroup (unless there's a fault on my PC or the Eternal September news server). https://skydrive.live.com/?cid=92a71a1c4b64fd41&id=92A71A1C4B64FD41!253#cid=92A71A1C4B64FD41&id=92A71A1C4B64FD41!255 It looks to me like no PPS is involved at all, just serial NMEA. It would be interesting to mark the 127.127.20.2 server as noselect, and I think that the system (then synced to the LAN servers) would show the variation in the NMEA timing more clearly. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ntpq -crv gives results in local time, not UTC
"Dave Hart" wrote in message news:cambsiyakrebebf3xkohy+v4dyavynqnmeymwhwhhu2ze1g1...@mail.gmail.com... On Thu, Apr 5, 2012 at 06:05, David J Taylor wrote: It seems that, on Windows at least, ntpq -crv gives results in local time, and not in UTC. Is that intended? Is there a switch for results in UTC? Yes, it's intentional. There is no built-in switch to use UTC but you can do it on most systems by setting/changing the TZ environment variable. On Windows: set TZ=GMT0 & ntpq -crv & set TZ= on Unix: env TZ=GMT0 ntpq -crv Of course, neither is necessary if your local timezone is UTC to begin with. I use UTC on my Windows systems because Windows misrepresents historical and future timestamps which are in the other half of the year, in DST terms. Cheers, Dave Hart Thanks, Dave. That's a pity, as I don't like the work-rounds. I know what you mean about file timestamps being different, although I wouldn't use the word "misrepresent". Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ntpq -crv gives results in local time, not UTC
It seems that, on Windows at least, ntpq -crv gives results in local time, and not in UTC. Is that intended? Is there a switch for results in UTC? ntp 4.2.7p265 Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ATOM falseticker with flag3 enabled
"David Lord" wrote in message news:t1bk49-6hi@me6000g.home.lordynet.org... [] I'm not sure which value you are referring to. From the "ntpq -p" billboard over a day, I see values of jitter of the GPS as low as 0.002 jitter No of 0.002156 0.003 50 0.004 22 0.005 4 0.006 4 0.007 1 0.012 1 0.014 1 0.025 1 "ntpq -c rv" for that system reports "precision=-19". ie 2^-19, but another couple of systems without PPS source are reporting "precision=-20" and I think that these two systems have done better than that when temperatures have not been as varied. David Feel the need for more than 3 digits here? David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] OK - You told me so! Amazing Sure gps performanceon real serial
Hi all, I finally got around to attaching a serial cable to the motherboard header on my desktop computer and attaching the Sure gps to it. This NTP+GPS has been a long and winding road, and has been much more difficult to get a handle on than I anticipated, including ordering a number of parts and waiting what felt like eternity to get them. Watched pot never boils, etc. WOW! I'm blown away as I'm now getting + / - 50 MICROSECOND performance. Yes, I know, old hat to you guys, but still news to me. I can't believe decades old comm technology works so much better than modern comm technology. [] Sincerely, Ron Ron, I'm delighted that it's lived up all the promises we made! Have fun! Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ANN: UK GPS Jamming update
Just wondering: 1) Is the UK govt doing this? The notice is from a UK Government agency. 2) Is the USA doing anything similar? I would be surprised if they were not, but they may have more remote areas to carry out such tests. 3) What's the purpose? I understand that it's for the military to see how they would work without GPS or on the event of GPS jamming. 4) Have you guys using GPS over there been affected? Sincerely, Ron Yes, see: http://www.bbc.co.uk/news/uk-scotland-highlands-islands-15242835 Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ANN: UK GPS Jamming update
I have received the following notice ___ NOTIFICATION OF GPS JAMMING EXERCISES SCOTLAND, NORTH AND WEST COASTS, 16-26th APRIL 2012 Dates: Between 16 to 26 April 2012 inclusive. Times: Intermittent for 1hr slots between 0800BST and 2130BST. Location of MULTIPLE jammers: A.The Little Minch and North Minch northwards from Waternish Point 57-36N 006-38W to Stoer Head 58-14N 005-24W, including Sound of Raasay and Inner Sound. B.Within 35 miles of Faraid Head 58-36N 004-46W. Frequency: A 24 MHz band centred around 1176.45 MHz (GPS L5), 1227.60MHz (GPS L2) and 1575.42MHz (GPS L1). Contact Details: In an emergency any vessel may request an abatement of jamming via VHF through Emergency cease jam via the CG, the Jamming Station (call sign: Loch Ewe / Cape Wrath GPS Jamming), or by telephone to Joint Warrior Duty Controller 01436 674321 ext. 4372. It is stressed that, as in previous exercises, Safety of Life operations will at all times take precedence over exercise activities. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] performance testing sure gps board via usb serialconverter
All these parameters and permutations are confusing, particularly if experimenting with Windows and Linux. Agreed! Thanks to David Taylor for encouraging me to experiment with interpolation, using the environment variable NTPD_USE_INTERP_DANGEROUS=1 to turn on and NTPD_USE_SYSTEM_CLOCK=1 to turn off. Does that apply to Linux by the way? No. In the past, I thought realtime priority for the NTPD process was causing problems. So, I've been experimenting with both priority and interpolation. Realtime is the default priority. The most accurate time source I have is my GPS. Internet, in my case, doesn't even come close. So, I'm testing min and max offsets of my computer's clock to the GPS polling every 8 seconds. The tests weren't too scientific nor too long, but I still saw some interesting results. 1) Interpolation ON , Above Normal Priority, + 1.00 / - 0.75 ms, Total Range 1.75 ms 2) Interpolation ON , Realtime Priority, + 0.99 / - 0.67 ms, Total Range 1.66 ms 3) Interpolation OFF, Above Normal Priority, + 1.21 / - 1.19 ms, Total Range 2.40 ms 4) Interpolation OFF, Realtime Priority, + 1.13 / - 1.02 ms, Total Range 2.15 ms Comparing lines 1 and 2, going from Above Normal to Realtime priority with interpolation on reduces range by .09 ms. Comparing lines 3 and 4, going from Above Normal to Realtime priority with interpolation off reduces range by .25 ms. Comparing lines 3 and 1, in that order, turning interpolation on at Above Normal priority, reduces range by .65 ms. Comparing lines 4 and 2, in that order, turning interpolation on at Realtime priority, reduces range by .49 ms. Conclusion, I'm leaving interpolation on, and I'm leaving the process at Realtime priority. [] Hopefully, someone will find this useful. Sincerely, Ron Yes, it's interesting to see the result, Ron. With the interpolation enabled, the errors in timestamping the pseudo-serial data should be very much reduced, but there is still the USB ~1 millisecond sampling interval left, so interpolation may only reduced the offset by a factor of around two at best. Good to see that you are now getting better results with real-time than simply above normal priority - it suggests that things are behaving as expected. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] YEA! My Sure Electronics GPS just arrived.
Hi David, See below. [] That's a great tip about PNG files. I never knew anything about them. They replaced GIF files for many purposes, and not only do they have full colour, they have better algorithms than GIF so may produce more compact files. IIRC the major reason for their existence was to bypass patents which someone threatened to enforce. At this point, I don't know if I'll even try to sync the GPS with the internet servers, since I'm getting more accurate time from the GPS than I can from the internet. I may change my mind if NTPD ends up clock hopping too much once I release the internet servers to run as a backup. I'm looking forward to playing with the real serial port on my other machine a bit. I'm not quite finished testing the USB port on this laptop though. Sincerely, Ron Yes, with the DCD over emulated USB that's what I would expect - it should beat most Internet connections. You might well find no clock hopping at all. Recall, though that usually clock hopping is NTP working to give you the best result from a selection of similar servers. Having the Internet servers even on minpoll=10 is a safety fallback. Prepare for a pleasant surprise when using a hardware serial port. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] consistent negative offset with Garmin GPS 18x LVCand FreeBSD
"Kenyon Ralph" wrote in message news:20120324223442.gd26...@kenyonralph.com... [text was an attachment] Please give details of your Internet connection. I wonder about asymmetrical trip delays. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] YEA! My Sure Electronics GPS just arrived.
"Ron Frazier (NTP)" wrote in message news:4f6dda72.30...@c3energy.com... [] Hi David, You appear to be up early. I'm curious to know what time this email says it arrived. If it says it arrived at about 1030, then that's my time. If it says it arrived at about 14:30, then that's your time. I am on UTC here, and the posting was made in the (very) early hours. Since I wrote that, it seems to have centered itself around zero. I now have a very nice + 1.2 ms / - 1.2 ms offset pattern. Since I've been struggling to get anything under 50 ms with other technology, this looks really sweet to me. http://dl.dropbox.com/u/9879631/Sure%20board%20first%20night%20pt1.jpg http://dl.dropbox.com/u/9879631/Sure%20board%20first%20night%20pt2.jpg Conversion of these images to jpeg reduced the clarity a bit, but you can still see what's happening. I vaguely recall that USB has a polling interval of ~1 millisecond. Additionally, unless you use interpolation, Windows timestamping introduces a further 1 millisecond quantisation in its timestamps of the USB data (that 0.977 ms jitter is the signature of plain Windows timestamps), so your +/- 2 milliseconds max seems to be of the correct order MICROSECONDS, did you say? I'm nowhere near that territory with everything going through a serial - USB converter. However, I'm quite happy with 1.2 ms under the circumstances. That millisecond polling is the limiting factor, go for a hardware serial port and the kernel-mode timestamping and you're an order or two better again. I am NOW assuming that my clock is more accurate than the internet clocks. I am NOW hoping that neither will appear to be drifting away and that nothing in the system will be having routine heart attacks. Fingers crossed. For the reasons mentioned above you could be up to a couple of milliseconds out in absolute terms. I notice there is a difference between my clock and the average internet clock reading. Hypothetically, even though mine is probably closer to UTC than those readings, if I wanted to shift my offset to match them, so NTP won't clockhop, how as long as the GPS is working, how would I do that? Here are my config lines: # COM5 57600 windows lines for testing gps selected as main source - gpgga 57600 baud server 127.127.22.5minpoll 3 maxpoll 3 # PPS fudge 127.127.22.5 flag2 0 refid PPS # PPS standard polarity server 127.127.20.5 prefer minpoll 3 maxpoll 3 mode 66 # NMEA fudge 127.127.20.5 time2 0. refid GPS1 # use WITH PPS Also, why doesn't the PPS show up in my status screen anywhere? I know it's working, based on the graphs. Sincerely, Ron Check the driver configuration. PPS requires the kernel-mode timestamping of the DCD line going active, and that's only available in Dave Hart's serial-pps driver/DLL. For the same PPS timesamps in other drivers would require e.g. USB providers to update their drivers as well, which isn't at all likely to happen. If you knew that the average delay between true start-of-second and your PC timestamping the USB/serial packet was 1.5 milliseconds, you could probably use something like: fudge 127.127.20.5 time2 0.0015 refid GPS1 Looking at your plot of peer offset, though, that might bring the best Internet server /nearer/ to zero offset. BTW: you may find that PNG is a better format for saving graphics - except for the lines which are very "noisy" and would increase the file size. PNG is lossless, and can produce quite small files of plots. That's one reason my program saves data in that format. I'm delighted with your results so far. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] YEA! My Sure Electronics GPS just arrived.
I now have the PPS circuit working on the Sure board. I have not soldered it yet. I just taped a jumper wire between the PPS test point at the edge of the board and the DCD pin 1 on the RS-232 port. The serial data is coming in through the Trendnet TU-S9 serial - USB converter, which is passing DCD. I'm getting + .5 / - 1.5 ms offsets. The PPS is nowhere to be seen on the statistics screen, but it is obviously working. I don't know why it's not more centered around zero, and maybe that will change. However, my total peak to peak range of offset variance is 2 ms, and that's coming through USB. If I can maintain that level of accuracy, and it's consistent with UTC, then I'm very happy. That's plenty good for my purposes. I still may try to run it through a real serial port on another machine just for kicks. Sincerely, Ron Ron, Yes, those were the sorts of figures I was seeing. http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html#usb The jitter I saw was about 45 microseconds for the USB/PPS against 2.3 - 3 microseconds for various serial-port/PPS. All figures from Windows XP. If the graphs there are anything to go by it seems that the offset varied between -0.15 to +0.3 milliseconds (very approximately). Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] peerstat update frequency
"A C" wrote in message news:4f6d5d8f.8080...@acarver.net... On 3/23/2012 20:48, unruh wrote: On 2012-03-24, A C wrote: How often should an individual peer write an entry to the peerstat log? Is it supposed to occur every time the peer is polled or only once every certain number of polls? Every time it is polled. (ntpd writes to the file, the peer does not do so.) Well that is precisely what is not happening. Dave Hart has already given you the correct answer. Sometime Bill's answers are wrong, possibly not based on the current NTP code. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] ANN UK: MSF 60KHz interruption - Mon Mar 26 - Fri Apr 06
Folks, I have received notice that the MSF 60 KHz signal from Anthorn, Cumbria, UK will be off-air 08:00 UTC Mon 2012-Mar-26 to 20:00 2012-Apr-06. The service may be off-air continuously during the period, but will be restored overnight and at the weekend whenever possible. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] YEA! My Sure Electronics GPS just arrived.
Hi all, YEA! My Sure Electronics GPS just arrived. I ordered on 03/05/12 and it arrived on 03/23/12, so it took 18 days. [] I have a question for someone with experience with the board. If I unplug the board, will it retain it's programming, or will it lose it? If it retains it, how long will it keep the data? If it loses it, how can I prevent that? Sincerely, Ron Good news, Ron. I did see one report here that the board /may/ not retain its programming, that's why I've made my NTP configuration work with the default settings. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] UK ANN: NOTIFICATION OF GPS JAMMING EXERCISES SALISBURY PLAIN, WILTSHIRE, 7TH MAY 2012
NOTIFICATION OF GPS JAMMING EXERCISES SALISBURY PLAIN, WILTSHIRE, 7TH MAY 2012 Dates: Between the 7th of May and the 11th of May 2012 (Inclusive). Times: : 0700 - 2000 GMT. Location of MULTIPLE jammers: Land based within 5km of N51° 12', W001° 58.5'. Frequency: A 24 MHz band centred around 1575.42MHz (GPS L1) Total Power: Up to 10 Watts EIRP. It is stressed that, as in previous exercises, Safety of Life operations will at all times take precedence over exercise activities. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"E-Mail Sent to this address will be added to the BlackLists" wrote in message news:jkgjpo$vf$1...@dont-email.me... [] I checked two typical desktops here: ntpq -c "rv &0" processor="x86", system="Windows", leap=00, stratum=3, precision=-21, ~477ns ? .. and I have one reporting -22! Hence the need for more investigation and understanding. loopstats' clock offset and RMS jitter are to the nano-second ? That should be good for up to maybe precision=-30 ? Here's a typical line: 56006 12567.480 0.003754344 7.420 0.000799395 0.036695 6 Precision of the fields: day: integer second: 3 digits, milliseconds offset: 9 digits, nanoseconds drift compensation: 3 digits (of parts per million) estimated error: 9 digits stability: 6 digits polling interval: integer precision=-19 is ~001.907us ? Would not a factor of 10 be hundreds of nano-seconds? Yes, for -19, but what about my -22 system? In any case, I was simply suggesting that the same data should be available through ntpq as through loopstats. The precision with which that data should be reported is not an issue in the bug report. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"unruh" wrote in message news:7RLar.8362$yd7.6...@newsfe15.iad... [] If your system had a precision of -22, I could understand your annoyance that the reporting was just to usec. But since it is -19, I have much less understanding of why you are getting upset. That is what I am trying to figure out. You claim that if the report were say precision -22 you would get more useful information. I am having trouble following your reasoning. I do have at least one system reporting -22 for precision. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"unruh" wrote in message news:uNJar.12581$qc3.8...@newsfe16.iad... [] Most likely I would be looking at a histogram of the reported offsets, and see whether it was gaussian, flat, or whatever, and how wide. I might learn something from that. No. Not if it is just noise. .. but until I see I won't know. [] precision is not accuracy. and where did I say it was? In science we teach students not to report unwarranted precision-- the precision should reflect the accuracy of the measurements. We keep getting measurements to the mm and reported precision to angstoms because that was what the calculator spit out. I hope you teach error estimation as well. I am not averse to reporting with a precion maybe up to a factor of 10 better than the accuracy, but any more is just silly and misleading (as you are demonstrating in believing that a greater precision would convey some extra information. Should you read what I wrote, including the bug report, perhaps you would see that I was quite happy for the number of reported digits to depend on the precision which NTP reports, but to keep things simple I suggested using the same reporting precision as is used in the loopstats, The present integer microseconds are no longer adequate for the faster and better of today's NTP systems. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"unruh" wrote in message news:xLHar.38386$iq1.34...@newsfe18.iad... [] Measure what? Why do you think that ntp reporting the offset with an extra three decimal points would allow you to measure anything? What in your mind would you expect to see in that output that would allow you to "measure" something that would tell you that the -19 was wrong? Remember ntpd DID measure something in order to determine that -19. What do you think the extra decimal places would give you? Most likely I would be looking at a histogram of the reported offsets, and see whether it was gaussian, flat, or whatever, and how wide. I might learn something from that. Others have reported precisions better than -19, and also have a need for greater reporting precision. There seems to be an impression out there that I'm trying to show something is wrong - I'm not. I suggested an enhancement so that the precision of ntpq matched that of the loopstats. That's all. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"Richard B. Gilbert" wrote in message [] Since this is an "all volunteer" service, the fastest, and maybe the only, way to get this enhancement is to write the code yourself! If you lack programming skills you could try paying someone to do it. Richard, I do have programming skills, just not in this language. But it's not just programming skills - it's understanding the architecture of NTP as well. Which bit to alter - and that was not obvious in this case. You will find that I have contributed quite a lot to NTP in terms of monitoring utilities, and in many hours of testing. With Dave Hart's help, I even managed to get NTP to compile once on my Windows system, but with my level of C skills you would not want any of my C code in a production release! Fortunately, someone has now done the programming work, as the requirement is not just mine alone. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"Harlan Stenn" wrote in message news:e1satsh-000mhb...@stenn.ntp.org... My take is the precision output might say your device is -19 so you know its accuracy is around 2/microseconds. But the offset several decimal places allows you to see its ever changing accuracy within that 2/microsecond band to a greater detail than just -1, 0, or 1 microseconds. I guess its just a matter of getting more granular details for cool MRTG charting. :) Except it's not - it's really just "noise" and one must be careful about interpreting it as "signal". H Until you can measure it you don't really know. Suppose the -19 reported by NTP isn't actually the correct value for the system? Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"Ron Frazier (NTP)" wrote in message news:4f69e531.7070...@c3energy.com... [] C) What your ntp plotter plots as the red line on the jitter tab with a loopstats file. Not sure how that's derived. Red-line: jitter straight out of the loopstats data. Scale on the left. Green line: same, but averaged over the time you select. Note that the scale is on the right-hand side, and is ten times that on the left. This so that peaks show more clearly on the raw graph. D) What your ntp plotter plots as the black line on the jitter tab with a loopstats file, a weighted moving average, presumably of the red line. The RMS variation of the offset in a one-hour period. Not sure this is particularly useful, quite honestly. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"unruh" wrote in message news:itmar.5841$yd7@newsfe15.iad... [] But -19 is about 2 microseconds if I understand it correctly. That means that the clocks are incapable of delivering more than about 2 microseconds of accuracy. What is you that last decimal digit of accuracy in the offset is thus pure noise-- dominated by clock reading noise. Why is it important for you then? When I can see the decimal places, then I will know whether the precision estimate is reasonable. Just getting values such as -1, 0, 1 microseconds is insufficient to make that call. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"Markus Schöpflin" wrote in message news:jkc7l7$o9o$1...@speranza.aioe.org... Am 20.03.2012 13:46, schrieb Harlan Stenn: On Mar 20, 3:45=A0am, "David J Taylor" wrote: Any chance of getting bug 2164 moving? =A0"Greater precision needed for n= tpq offset report". =A0http://bugs.ntp.org/show_bug.cgi?id=3D2164 Patches welcome, otherwise we'll get to it as soon as somebody gets to it. I have attached two patches to that ticket, not sure if it's all that is needed for the ticket to be fixed. The (smoke tested) patch for ntpq seems OK, but I have no idea if the (only compile tested) patch for ntpd is really that trivial. Markus Brilliant, Markus. Another step forward. I hope that can be put into the next development release. Many thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
On Wed, Mar 21, 2012 at 06:49, David J Taylor wrote: (Is jitter RMS, SD, peak-to-peak?). NTP's jitter is root mean squares of offsets from the clock filter register (last 8 responses, more or less). Dave Hart Thanks, Dave. Makes good sense. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"Ron Frazier (NTP)" wrote in message news:4f692255.2020...@c3energy.com... On 3/20/2012 11:21 AM, David J Taylor wrote: [] You /will/ see variation in the serial output from the Sure device, as you will in many NMEA devices. For the Sure device, one measurement is here: http://www.leapsecond.com/pages/MG1613S/ under the heading "NMEA Latency". The graph here is 100 milliseconds full scale. http://www.leapsecond.com/pages/MG1613S/nmea-jitter-1.gif That's funny, there's this line in the text. "In a 15 minute run (900 seconds) the mean latency was 350.2 ms with a standard deviation (jitter) of 10.7 ms. " Then there's the graph, which seems to show a variance in NMEA start time of 75 ms or so. The two seem to contradict each other. How so? Are you taking the peak-to-peak figures from the graph and comparing it to the standard deviation? SD isn't a peak-to-peak value. You already mentioned the Garmin previously, and the Sure now, and I have reports of similar NMEA drifting behavior from other SIRF units. So, it appears that most, if not all GPS's exhibit a variance in the timing of NMEA data of 50 to 120 ms or so. That would definitely put a limit on what you could do with NMEA only data. Yes, in typical GPS receivers the NMEA data is only accurate to a second - it says where the unit was at the UTC second preceding the data. I don't believe that jitter in NMEA output time is limited to one particular chipset. (Is jitter RMS, SD, peak-to-peak?). Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"unruh" wrote in message news:dG5ar.18461$pc1.11...@newsfe11.iad... [] No confusion. I understood completely. Ron had a machine on GPS which ran away. You got a report of a 1 sec slippage. The question is whether or not a 1 sec slippage in the GPS could trigger a runaway on a machine which also had LOCL as a server. OK. I simply do not believe that the GPS sudenly went wild and delivered time at a rate 1000 times the UTC rate. It seems unlikely. Something on his system triggered and instability, and all he had running was a GPS and the LOCL server. Now, usually the machine would take the GPS signal and it certainly could not engage in that kind of runaway behaviour. It could however engage in something like a 1 sec slippage. How could that trigger an instability? I would regard a system which was not at least somewhat protected against failure of a GPS device as not being correctly configured. Perhaps the NTP simulator could be used to predict behaviour in the case you suggest, but I have no experience with that tool. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"Harlan Stenn" wrote in message news:e1sa6us-000kpj...@stenn.ntp.org... David wrote: 2164 needs discussion, unless altering the number of significant digits in the ntpq output wouldn't break anything. Do we need to have this discussion? I have looked through ntpq.c, but I can't see where the number of decimal digits in the output for offset is set. I'd be inclined to do what we do for sntp, which is drive the number of emitted digits based on the precision of the time. H Yes, I agree that makes sense. I would wish to see at minimum the decimal point and tenths of milliseconds. On the system I want to monitor, the precision is reported as -19, but the offsets need at least four decimal places of milliseconds to be plotted with reasonable accuracy (i.e. tenths of microseconds are needed). Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"unruh" wrote in message news:Ur4ar.15722$iq1.15...@newsfe18.iad... On 2012-03-20, David J Taylor wrote: "unruh" wrote in message news:d13ar.7952$gv1.7...@newsfe12.iad... [] It is really really hard to imagine any gps device doing that. Yes, I agree, and yet what just popped up in my mail box but a reference to: "an inexplicable 1 second slip of 3 GPS based NTP time sources". I have, of course, asked for more details! A one second slip I could understand-- eg Gamin 18x reporting over 1 second after the associated second would lead to that. But a computer advancing at an hour per tick is way beyond that. Perhaps the 1 second slip tickled a bug in ntp with the LOCL clock-- where the system then saw the GPS as a false ticker, went to LOCAL with a bad rate, and compounded the rate error by some sort of runaway process. You are confusing two events here. Ron had a problem with the PC running fast. This was a separate incident where there was a 1 second slippage. When and if I get more details I will post them here. There is no suggestion that the two are related. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"unruh" wrote in message news:d13ar.7952$gv1.7...@newsfe12.iad... [] It is really really hard to imagine any gps device doing that. Yes, I agree, and yet what just popped up in my mail box but a reference to: "an inexplicable 1 second slip of 3 GPS based NTP time sources". I have, of course, asked for more details! Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
[] David Taylor is right that it is normal for Windows to keep running the clock at whatever rate was last set after the program setting the rate goes away. It's also true that Windows does not have any rate limits itself -- you can easily tell Windows to advance the clock 1 usec per tick (nominally 15.625 msec), one hour per tick. Unless I misread the nt_clockstuff.c code, it shouldn't be possible to get ntpd to set the Windows clock rate more than 500 PPM from nominal. Thanks, Dave Hart Dave, How does NTPD_TICKADJ_PPM affect this? If that was set to -800, for example, wouldn't the adjustment range be -300/-1300 rather than +/-500? Or are you including NTPD_TICKADJ_PPM in "nominal". Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
It seems that the types of different variables are stored in a table, and "offset" has type FL. Latter on, there is a block of code like this: case FL: output(fp, name, lfptoms(&lfp, 3)); break; case FU: output(fp, name, ulfptoms(&lfp, 3)); break; case FS: output(fp, name, lfptoms(&lfp, 3)); break; Here, the lfptoms()/ulfptoms() functions convert NTP's internal fixed point format into a string. I think that the 3 is the number of significant figures. You can change these, but it seems that the control messages are such that they only have 3 significant figures included in them. David. Thanks, David. Those don't seem to be in ntpq.c (at least 4.2.7p134), so no wonder I couldn't find them. But if the control messages are limited to microseconds, this problem is deeper than I first thought. I suppose that's saving on bandwidth by a few bytes? Cheers, David T ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"Ron Frazier (NTP)" wrote in message [] Hypothetically speaking, what if I don't want it to distribute time if it's working in internet mode? Run a Perl script one a minute, looking for the GPS line in ntpq -p output, and if the tally code isn't "*" (or whatever, get it to run: "net stop ntp" Non time server machines GPS (if attached) Local time server (if available) Internet as backup However, I only plan to do that after thoroughly testing the GPS by itself for a week or two to see if it's stable. I originally had the internet servers on with this unit. It completely surprised me by having this tendency to drift apparently and have periodic heart attacks. It's not a time GPS, so one could argue that it's not to be trusted. Unfortunately, this odd behavior may exist in all SIRF III and possibly other SIRF units. Unlikely, as there are several GPS receivers with PPS outputs listed using that chipset. It was only by turning off the internet servers that I was able to get some clean graphs of exactly what the GPS was doing. When I had the internet servers enabled, once the GPS starting acting odd, which it shouldn't do at all, NTPD would clock hop to the internet. Normally, that would be OK. However, as discussed previously, even my errant GPS is more accurate over the short term than the internet for me. With the internet conection, I get + / - 50 ms variations in time over a span of an our. With the GPS, I get + / - 60 ms variations over several days, with a few wild corrections during its heart attacks. Those are two bad choices, but I think I'd still rather run on the GPS. Your choice, of course. The only way I can prevent clock hopping is by noselecting the internet servers. What's the problem with the clock changing to Internet servers? It will change back again when the GPS returns to an acceptable state. Even if I end up with internet servers turned on, which I expect to, I think it's much better to know about these GPS anomalies before putting it into long term service. Anybody considering using a SIRF III or maybe even any SIRF unit for timekeeping should be warned by my experience, test the unit, and make sure it's up to the task. These problems could even affect SIRF units with PPS outputs, although I don't know. I'll probably decommission this unit from timekeeping duty and relegate it to navigation duty, although I'm not sure how trustworthy it is for that when it's throwing a temper tantrum. You want to say all SiRF chipsets are bad on the basis of testing one manufacturer's implementation, and in a way which the software supplier doesn't recommend? I've already committed to getting better (hopefully) equipment. (Shipping from Hong Kong or where ever seems to take a LONG time when you're waiting on something.) 2-3 weeks, and I'm an impatient sort as well! Hopefully, the Sure board will be much more stable and reliable. I'm planning to do the same extensive testing on the Sure for a week or two. I'll start out just plugging the Sure into my serial - USB converter using the same com port as the Globalsat unit was running on. I want to see how it does with NMEA only data for a while. I'm hoping NOT to see substantial drifting from UTC and NOT to see any heart attacks every few days. I expect lots of jitter, since a number of variable length sentences are being output. Then, I plan to turn off all but GPGGA and test some more, and maybe tinker with the baud rate. Then, if I can solder the board without killing it, I'll engage PPS through the serial - USB port and test that for a while. Then, I'll try it with PPS and real serial on my other computer, the only one with a serial port. You /will/ see variation in the serial output from the Sure device, as you will in many NMEA devices. For the Sure device, one measurement is here: http://www.leapsecond.com/pages/MG1613S/ under the heading "NMEA Latency". The graph here is 100 milliseconds full scale. http://www.leapsecond.com/pages/MG1613S/nmea-jitter-1.gif Hopefully, when I'm done, I'll have a qualified unit running stably and accurately for the whole network to use. I've acquired a case and some hardware to mount the device similar to yours. Once I learned that it was only 3" x 3", that made me nervous as far as soldering and all, but we'll see what happens. If in doubt, find someone who is used to working on such units. You could try Bill Unruh's suggestion to start with. By the way, do you think I should update to Dave H's latest binaries? I'm at 4.2.7p259 on Windows. Almost all these discussions have been about Windows. Linux is a whole other ballgame. The NTPD there from the repositories is about 2 years old, and I'm reluctant to go outside the repositories because of the numerous problems it creates. One very serious Linux user on a local message board said even he doesn't compile his own programs because
Re: [ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
"Harlan Stenn" wrote in message news:e1s9ysb-000kqp...@stenn.ntp.org... On Mar 20, 3:45=A0am, "David J Taylor" wrote: > Any chance of getting bug 2164 moving? =A0"Greater precision needed > for n= tpq > offset report". > > =A0http://bugs.ntp.org/show_bug.cgi?id=3D2164 Patches welcome, otherwise we'll get to it as soon as somebody gets to it. > While I'm asking, nothing seems to have happened with bug 1577 in > over 18 > months. =A0"Request that SNMP support be added for the Windows port" > > =A0http://bugs.ntp.org/show_bug.cgi?id=3D1577 > > I have made both of these "enhancement" level, which may be why they > are > stuck. =A0Should I boost the importance? I second Bug Ticket: 2164 I suspect a bump would not help, for reasons cited above. I will say (knowing full well that I am not a windows guy) that we use net-snmp for this for Unix, and it sure looks to me like that code should build under Windows. What we need is somebody to build the net-snmp code under Windows and then build the ntpsnmpd piece as well. Again, paches welcome, or sooner or later somebody will get to it. H Harlan, Thanks for your reply. If I did "C" I would happily submit patches, but my software is in Delphi for higher productivity and a most helpful user community. I find "C" almost unreadable. 2164 needs discussion, unless altering the number of significant digits in the ntpq output wouldn't break anything. Do we need to have this discussion? I have looked through ntpq.c, but I can't see where the number of decimal digits in the output for offset is set. I would give priority to 2164 over 1577, but I suggested 1577 for the Google Summer of code and received precisely zero response! I do see that net-snmp does include a note for Windows users: http://www.net-snmp.org/download.html so adding support doesn't involve starting from scratch. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Any chance of getting bugs 2164 and 1577 moving?
Any chance of getting bug 2164 moving? "Greater precision needed for ntpq offset report". http://bugs.ntp.org/show_bug.cgi?id=2164 While I'm asking, nothing seems to have happened with bug 1577 in over 18 months. "Request that SNMP support be added for the Windows port" http://bugs.ntp.org/show_bug.cgi?id=1577 I have made both of these "enhancement" level, which may be why they are stuck. Should I boost the importance? Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] PSYCHO PC clock is advancing at 2 HR per second
"unruh" wrote in message news:JDU9r.22132$_c5.11...@newsfe09.iad... [] Of course the question still is why in the world did the system go nuts when it was on Local. That itself should not have happened. If some software had told the system clock to run fast, it simply stays running fast, even on Local. Ron is using a single GPS device, over USB, without the backup of a few Internet servers to stop such a thing happening, and the GPS has already shown itself to be problematical. NTP would normally have simply rejected the errant GPS data and not cause the PC clock to run wild, but without the Internet servers as backup, what is NTP to do? I don't think it has a choice other than to believe the GPS, even if it's incorrect or faulty. Ron, perhaps in the future you could adopt a similar configuration to one I've mentioned before - add some Internet servers with a long polling interval as a second opinion for NTP: _ server server 0.us.pool.ntp.org minpoll 10 iburst server 1.us.pool.ntp.org minpoll 10 iburst server 0.uk.pool.ntp.org minpoll 10 iburst server 1.uk.pool.ntp.org minpoll 10 iburst _ using servers [network] local to yourself, of course. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] site with lots of GPS's and accessories
Hi all, I was doing some GPS research and found this site with lots of GPS's and accessories. Just thought I'd pass it along. http://www.gpssensors.com/ I don't know which ones are timing GPS's. Sincerely, Ron Ron, The one I recognise as being a timing GPS with PPS and suitable for NTP is one which isn't one that page, but here: https://www.starlite-intl.com/Detail.asp?pid=2320 Same company. US $61 Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTPD_USE_INTERP_DANGEROUS was ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f65ee78.20...@c3energy.com... I'm forking the subject line, which didn't really seem relevant any more. more below [] http://www.satsignal.eu/ntp/Win-8+Internet.html [] From my point of view, those look pretty good. Those peerstats graphs come in pretty handy. It is an unloaded system, but may show what NTP can do at best using just Internet servers in a domestic Internet-linked environment. [] What's the dangerous part? Are we just talking lots of CPU churning? If so, can I just shut down NTP and tweak it? Sincerely, Ron Ron, It's just about performance. Windows XP performed better when NTP tried to interpolate the ~15 millisecond timer ticks. Windows Vista performed significantly worse when that interpolation scheme was used, so it was conditionally disabled. In early tests of Windows-7, performance seemed better, but the OS code which changed the timer interval didn't start at the same time as NTP, so sometimes NTP made the wrong choice. Here's what Dave Hart said at that time: "I thought I understood the problem with ntpd interpolation on Vista/Win7 to be caused by the OS scheduling granularity being insufficiently finer than the native clock granularity, so that the interpolation thread's sampling of counter/native clock correlations was nearly always occurring at the same relative point between two native clock ticks, rather than being nicely spread around. Being spread around is important because the algorithm chooses the sample nearest the prior native clock tick when converting a counter value to an interpolated time." So there's no problem with high CPU or anything like that - simply worse offset and jitter. You can also force interpolation off by setting: NTPD_USE_SYSTEM_CLOCK=1 or on with: NTPD_USE_INTERP_DANGEROUS=1 Delete the environment variables not in use. The actual value they are set to doesn't matter, it's only the presence or absence which is tested. After setting these SYSTEM environment variables, simply restart the NTP service to see the change. I see these settings as ones for experimenters, and they should not be needed in normal use. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTPD_USE_INTERP_DANGEROUS was ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f65ee78.20...@c3energy.com... I'm forking the subject line, which didn't really seem relevant any more. more below [] http://www.satsignal.eu/ntp/Win-8+Internet.html [] From my point of view, those look pretty good. Those peerstats graphs come in pretty handy. It is an unloaded system, but may show what NTP can do at best using just Internet servers in a domestic Internet-linked environment. [] What's the dangerous part? Are we just talking lots of CPU churning? If so, can I just shut down NTP and tweak it? Sincerely, Ron Ron, It's just about performance. Windows XP performed better when NTP tried to interpolate the ~15 millisecond timer ticks. Windows Vista performed significantly worse when that interpolation scheme was used, so it was conditionally disabled. In early tests of Windows-7, performance seemed better, but the OS code which changed the timer interval didn't start at the same time as NTP, so sometimes NTP made the wrong choice. Here's what Dave Hart said at that time: "I thought I understood the problem with ntpd interpolation on Vista/Win7 to be caused by the OS scheduling granularity being insufficiently finer than the native clock granularity, so that the interpolation thread's sampling of counter/native clock correlations was nearly always occurring at the same relative point between two native clock ticks, rather than being nicely spread around. Being spread around is important because the algorithm chooses the sample nearest the prior native clock tick when converting a counter value to an interpolated time." So there's no problem with high CPU or anything like that - simply worse offset and jitter. You can also force interpolation off by setting: NTPD_USE_SYSTEM_CLOCK=1 or on with: NTPD_USE_INTERP_DANGEROUS=1 Delete the environment variables not in use. The actual value they are set to doesn't matter, it's only the presence or absence which is tested. After setting these SYSTEM environment variables, simply restart the NTP service to see the change. I see these settings as ones for experimenters, and they should not be needed in normal use. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTF: NTP and PTPd are in GSoC 2012
"Harlan Stenn" wrote in message news:e1s8mc4-000dep...@stenn.ntp.org... Network Time Foundation, Inc. is pleased to annouce it has been accepted as a mentoring organization for GSoC 2012. We're looking for student projects involving Network Time, and the two biggest efforts we expect are for the Network Time Protocol Project (NTP) and the Precision Time Protocol Daemon Project (PTPd). Please see http://www.google-melange.com/gsoc/homepage/google/gsoc2012 for more information, or visit http://www.networktimefoundation.org for some quick links. -- Harlan Stenn http://ntpforum.isc.org - be a member! I suggest getting SNMP working for the Windows NTP port. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Rob" wrote in message news:slrnjmbdn3.9ce.nom...@xs8.xs4all.nl... Uwe Klein wrote: Regular DSL here has quite large and spread line delays though speed is much higher delay is similar or slightly larger than forex ISDN. PING 87.186.242.38 (87.186.242.38) 56(84) bytes of data. ( my first pingable outside node ) 64 bytes from 87.186.242.38: icmp_seq=1 ttl=254 time=48.3 ms 64 bytes from 87.186.242.38: icmp_seq=2 ttl=254 time=34.3 ms 64 bytes from 87.186.242.38: icmp_seq=3 ttl=254 time=77.4 ms 64 bytes from 87.186.242.38: icmp_seq=4 ttl=254 time=70.8 ms 64 bytes from 87.186.242.38: icmp_seq=5 ttl=254 time=108 ms 64 bytes from 87.186.242.38: icmp_seq=6 ttl=254 time=89.0 ms 64 bytes from 87.186.242.38: icmp_seq=7 ttl=254 time=109 ms 64 bytes from 87.186.242.38: icmp_seq=8 ttl=254 time=64.1 ms 64 bytes from 87.186.242.38: icmp_seq=9 ttl=254 time=76.1 ms 64 bytes from 87.186.242.38: icmp_seq=10 ttl=254 time=145 ms 64 bytes from 87.186.242.38: icmp_seq=11 ttl=254 time=199 ms 64 bytes from 87.186.242.38: icmp_seq=12 ttl=254 time=104 ms 64 bytes from 87.186.242.38: icmp_seq=13 ttl=254 time=247 ms 64 bytes from 87.186.242.38: icmp_seq=14 ttl=254 time=104 ms Funny network... I can ping the same address over my own DSL and get lower and more stable ping than you do: ping 87.186.242.38 PING 87.186.242.38 (87.186.242.38) 56(84) bytes of data. 64 bytes from 87.186.242.38: icmp_seq=1 ttl=245 time=34.7 ms 64 bytes from 87.186.242.38: icmp_seq=2 ttl=245 time=36.3 ms 64 bytes from 87.186.242.38: icmp_seq=3 ttl=245 time=35.3 ms 64 bytes from 87.186.242.38: icmp_seq=4 ttl=245 time=33.6 ms 64 bytes from 87.186.242.38: icmp_seq=5 ttl=245 time=34.8 ms 64 bytes from 87.186.242.38: icmp_seq=6 ttl=245 time=35.8 ms 64 bytes from 87.186.242.38: icmp_seq=7 ttl=245 time=34.2 ms 64 bytes from 87.186.242.38: icmp_seq=8 ttl=245 time=35.3 ms 64 bytes from 87.186.242.38: icmp_seq=9 ttl=245 time=33.0 ms 64 bytes from 87.186.242.38: icmp_seq=10 ttl=245 time=34.2 ms ^C --- 87.186.242.38 ping statistics --- 10 packets transmitted, 10 received, 0% packet loss, time 9043ms rtt min/avg/max/mdev = 33.069/34.776/36.339/0.943 ms Pinging something local in my provider yields stable pingtimes within 13-14 ms... Maybe your provider still uses old ATM technology between the subscribers and the DSL router, and the network is heavily overbooked. This is, however, not a generic property of DSL. DSL can have stable roundtrip times. .. and from Edinburgh: ping 87.186.242.38 Pinging 87.186.242.38 with 32 bytes of data: Reply from 87.186.242.38: bytes=32 time=43ms TTL=239 Reply from 87.186.242.38: bytes=32 time=44ms TTL=239 Reply from 87.186.242.38: bytes=32 time=46ms TTL=239 Reply from 87.186.242.38: bytes=32 time=50ms TTL=239 Ping statistics for 87.186.242.38: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 43ms, Maximum = 50ms, Average = 45ms That's at 11:07 on a Sunday morning. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f65006d.4090...@c3energy.com... [] Come to think of it, my comment about the polling interval not increasing may only apply to a local refclock, not a local server. You may be right - all the servers on this test system are Internet servers. Can you elaborate more about what NTPD_USE_INTERP_DANGEROUS does? Sincerely, Ron Overnight results are here: http://www.satsignal.eu/ntp/Win-8+Internet.html As you can see, jitter is under a millisecond, with the local (noselect) server showing about half a millisecond of jitter, and the Internet servers between about 3 and just over 6 milliseconds. NTPD_USE_INTERP_DANGEROUS if set, forces interpolation on Windows. With Windows XP or earlier, Interpolation works well, but not on Vista or later, so under certain conditions, NTP disables interpolation as mentioned here: http://lists.ntp.org/pipermail/questions/2011-November/030904.html You can enable interpolation, and you may get better results. If not, jitters will have a floor of about 0.977 milliseconds. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
I prefer fiber: 50/50 Mbit, very consistent ping times of a couple of ms to most no.pool.ntp.org servers. :-) Cost is about $75/month. Terje Maybe I should move to Norway! You are lucky! I pay US $48 (equivalent) for my 30/1 service! Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f64d793.9010...@c3energy.com... [] Hi David, I'm not sure what will happen if you simultaneously prefer and noselect the local server. Assuming the local stratum 1 server is the most stable time source, you'll get a much better picture of what the internet servers are doing relative to it if you allow it to be selectable as well as being preferred. When you graph it, if the local server is the active clock, all the lines for the internet servers will be gathered around and relative to the local server. When I tried to do things the other way around, with an internet server preferred, the graph looked awful because there was so much variation. Also, if your local server starts reporting time that looks too far from the internet servers, regardless of who's fault it is, ntp will clock hop over to the internet servers. I don't THINK your internet servers will ever poll above their default minpoll value of 6, or 64 seconds. I realize you don't have a gps attached to this pc, but the iburst lines reminded me of something. I read somewhere that having iburst on internet server lines, if a local gps is attached, could prevent the PC from synchronizing to the gps before it synchronizes to the internet. On my pc with the gps attached, I don't use the iburst command. Sincerely, Ron Ron, The local stratum-1 server shows without a tally code against it in the ntpq -p output, so it's being recorded in the peerstats, but not used for syncing. The noselect msut override the prefer. After about three hours running, the Internet servers are all at 512 seconds poll interval. The averaged jitter has been below 1 millisecond for the last couple of hours. The offset is reporting between -0.7 and -1.8 milliseconds, and the frequency is stabilising very nicely (because of the long poll interval). I'll leave this running overnight and tomorrow to see how it handles temperature changes and any Internet access changes, and to get a few more points on the graph. One caveat is that I am using the most recent NTP (ntpd 4.2.7p263 from Dave Hart's download page), and that with Windows-8, it may be using the new precision time system call. From my own tests, this is similar, on earlier versions of NTP, to setting the environment variable NTPD_USE_INTERP_DANGEROUS, thus forcing the NTP time interpolation to be used. The configuration I have is: - cable modem (with built-in router, but working as a bridge by putting my own router in a device in the DMZ). - Samknows network monitor (modified WRT54GL router) - WRT54GL router running DD-WRT firmware - Netgear 8-port consumer 1 Gb/s switch (G5108) - wired connection to ~2 year old laptop PC I only mention this to show that (a) it's not a direct connection and (b) there's no wireless involved. My aim here is simply to see what performance may be had with just Internet servers. The PC is only running NTP and monitoring software - no user programs and no interactive work, so it is a best-case scenario. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
You'd get less jitter with DSL. -- John Hasler John, You have piqued my interest. I have just set up a Windows-8 PC with an ntp configuration not dissimilar to Ron's, in that it's using purely Internet servers but trying to monitor a local stratum-1 server as well. In essence: __ # Local stratum-1 Free BSD server server 192.168.0.3 iburst minpoll 5 maxpoll 5 prefer noselect # Seven external servers: server x.x.x.uk iburst server y.y.y.uk iburst server 0.uk.pool.ntp.org iburst server 1.uk.pool.ntp.org iburst server 2.uk.pool.ntp.org iburst server 0.nl.pool.ntp.org iburst server 1.nl.pool.ntp.org iburst __ The performance will appear here: http://www.satsignal.eu/mrtg/performance_torvik.php It will be interesting to see whether the Internet servers poll period increased from 64s (I'm hoping that the 32s poll on the local server won't affect the Internet ones), and what level of jitter is achieved. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"John Hasler" wrote in message news:87sjh7mlqs@thumper.dhh.gt.org... David J Taylor writes: But in the UK from Virgin Media I have 30 Mb/s down, 1 Mb/s up. I have been promised an upload speed increase about 18 months ago to 2 Mb/s up, which is more sensible... Such a very high cable download speed is a peak burst speeds on a shared medium. Your sustained performance is not likely to be more than a fraction of it. Speed tests from a number of sites show 30 Mb/s, and that's over several seconds. I downloaded the Windows-8 64-bit ISO recently, and the 3,583,707,136 bytes took 48 minutes, 24 seconds, which I make about 7.4 Mb/s, and the 32-bit ISO was 2,711,396,352 bytes in 27 minutes, so about 13.4 Mb/s. That was without any download accelerator (no multiple connections). Not ideal, but I prefer cable to ADSL. You'd get less jitter with DSL. -- John Hasler DSL or ADSL? But I haven't checked the jitter on the cable modem link for a long time, since I installed the GPS receivers. Thanks, John. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Terje Mathisen" <"terje.mathisen at tmsw.no"> wrote in message news:is9e39-6ve2@ntp6.tmsw.no... [] You should never accept much more than 10:1 speed difference between down and up. Terje "Should" - I agree. But in the UK from Virgin Media I have 30 Mb/s down, 1 Mb/s up. I have been promised an upload speed increase about 18 months ago to 2 Mb/s up, which is more sensible, but that increase hasn't yet been delivered. I am also promised an increase within the next year which doubles my existing speeds, giving 60 Mb/s down and 4 Mb/s up. Not ideal, but I prefer cable to ADSL. No wonder I have four GPS devices connected to 5 PCs! Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Loopstats update - how often?
"unruh" wrote in message news:Fdo8r.12214$v11.9...@newsfe20.iad... [] The clock filter selects the data with the smallest round trip time, to fix the problem with asymmetric round trips (on the theory tht the shortest time is more likely to be symmetric round trip). The filter is 8 items deep, and thus on average it selects the same item the whole time it is in the clock filter. Ie, on average a bit less than 7 out of 8 inputs are thrown away (it is actually avout 80% that are thrown away). This is for network polled items where round trip time makes sense. For refclocks about 40% are thrown away to get rid of "popcorn" deviations. (non-gaussian large offsets) as I understand it. Thanks, Bill. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f61e4df.4080...@c3energy.com... [] I mainly meant that operating conditions will vary the frequency of the oscillator. Speaking of which, is there a way to run ntpd and have it NOT adjust the clock at all, but still generate stats files, so I can monitor the clock frequency just based on the computer usage and nothing else? Pass. What happens if everything is "noselect"? Can you elaborate on that power saving frequency thing? Is that the thing in the control panel where you set the minimum and maximum cpu frequency? Likely, yes, but it varies between computers, chip makers (under different trade names), and BIOS makers. For best timekeeping, you want no clock speed variation. [] http://www.satsignal.eu/mrtg/performance_bacchus.php Wow, if I'm reading that graph right in the last link, that cpu usage spike sent your clock variation from about 100 us to 4000 us. That's amazing, and frustrating. The offset went from zero, to approximately +1.2 milliseconds. As MRTG can't plot negative numbers (it was designed for network throughput), I add 3.0 milliseconds to the reported offsets before plotting, as the left axis label says. So the range of the graph is +/- 3.0 milliseconds, plotted as 0 to 6ms. I thought all 32 bit Windows had the same kernel. You could try this defragger. I've had good luck with it, but I'm not sure which older systems it works on. http://www.auslogics.com/en/software/disk-defrag/ [] Sincerely, Ron Thanks for the suggestion, Ron, but that software, like most others, needs XP or higher. I actually use that program on one of my PCs, as it can also be called from the command-line to defragment files or directories. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] NTP, SNMP on FreeBSD 8.2
"David J Taylor" wrote in message
news:jjqdat$82m$1...@dont-email.me...
Folks,
I'm interested to know whether my install of NTP on FreeBSD 8.2 includes
SNMP support or not. If it doesn't, then I may try a recompile, but
first:
1 - can anyone point me to the correct place to download the appropriate
MIB? I did find:
http://tools.ietf.org/html/draft-ietf-ntp-ntpv4-mib-07
but the MIB information is interspersed with page headers, and whilst I
did try and edit it, I can't be sure it compiled, and hence a plain MIB
would be preferable. I did look elsewhere but only found Meinberg and
Cisco MIBs which could be proprietary.
2 - In the absence of a properly compiled MIB, can anyone point me to a
numeric OID which should be visible if NTP/SNMP is running? Ideally,
the OID corresponding to:
ntpq "-c rv 0 offset"
I can then use GetIF (or whatever) to look for that OID from my FreeBSD
ssytem.
Thanks,
David
OK, I found the MIB in the source distribution (as ntpv4-mib.mib, 15 Oct
2010), but it does not compile. I get an error at line 525, which is the
SYNTAX line below.
Error message:
__
ntpAssocAddressType OBJECT-TYPE
SYNTAX InetAddressType { ipv4(1), ipv6(2), ipv4z(3), ipv6z(4) }
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The type of address of the association. Can be either IPv4 or
IPv6 (both with or without zone index) and contains the type of
address for unicast, multicast, and broadcast associations."
::= { ntpAssociationEntry 4 }
__
Is this a bug, or a fault in my MIB compiler (GetIF 2.3.1)?
I'd still appreciate knowing the OID for:
ntpq "-c rv 0 offset"
Thanks,
David
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Re: [ntp:questions] Sure gps looses all sattelite fixes
Is that unit compatible with the Sure board? Wouldn't you need some sort of antenna connector adapter? Will the Sure board provide power to it? Sincerely, Ron - compatible, probably. Is +26 gain dB enough? It's the lower end of specifications for puck antennas. - adapter required, yes. - the Sure board includes +5v for the puck. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Loopstats update - how often?
On Thu, Mar 15, 2012 at 07:56, David J Taylor <> wrote: If I have a configuration including: _ server 192.168.0.7 minpoll 5 maxpoll 5iburst server 0.uk.pool.ntp.org iburst minpoll 10 _ how often should the loopstats be updated? I was expecting something near to every 32 seconds, but it seems that sometimes it can be more than 64 seconds. Is that correct? Ignoring the pool server, it could be as much as 32 * 8 seconds between loopstats updates. Some polls of 192.168.0.7 will not change the offset estimate for that peer, as an older entry in the clock filter register is preferred over the latest. Cheers, Dave Hart That explains what I am seeing, Dave. Makes sense not to repeat unchanging data! Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f61168b.8030...@c3energy.com... [] PS to my prior message. I don't think the problem so much is the delay to the internet servers, or even to get out of my house. NTPD is supposed to take care of that as long as it's pretty much symmetrical. I think the problem is that the Windows clock is like a wild tiger that doesn't want to be tamed and which is running every which way. Windows is not designed as a real-time OS, and its timekeeping is not as good as other systems, but with one good local server you can sync Windows PCs to that server with something like: minpoll 5 maxpoll 5. Obviously, you would not do that over the Internet without permission. For whatever reason, cpu load, heat, cosmic vibrations, whatever, the intrinsic frequency of the windows clock is always changing. In order to avoid beating up on the internet servers too much, I have to poll them at least every 4 minutes apart. If you let it, NTPD will extend that out to 16 minutes or more. So, when the clock source is polled, say the PC clock is too fast, so NTPD slows it down. Then, when you poll the clock source again, say the PC clock is too slow, so NTPD speeds it up. Because of the varying intrinsic frequency of the clock, you can never find a clock speed that just works, because then the system goes and changes, by changes in the oscillator, how much time passes at those particular settings. It's a battle you cannot win. By polling my GPS every 8 seconds, I can keep the clock under control based on it's current needs which are varying second by second. Of course, when discussing internet servers, 30 ms of jitter doesn't help any. Windows itself doesn't vary the clock frequency unless you enable the power-saving frequency of the chipset. What I /have/ seen on Windows is poorly written third-party drivers which hold off interrupts for too long or are otherwise badly behaved, and chipsets or motherboards which are equally unfriendly. I have one application which can ruin timekeeping, given half a chance! Note the scale on PC Gemini which has an AMD processor on an ASUS A8N SLI motherboard. +/- 100 ms, not +/- 3 ms. I see large offset steps, which NTP tries its best to keep up with. [] The point is, that it's a continually moving target. The windows clock is the same way. It never runs at the same frequency from minute to minute. Even if you get it running right one minute, it's wrong the next. All PCs are a continually moving target! Some move more than others, but give a good PPS source, the major variation on even Windows PCs is due to temperature fluctuations. Let's take, for example, the TAZ computer I mentioned earlier. Forget GPS for the moment. With the default settings, NTPD will eventually be polling the internet server every 16 minutes. The problem is not exclusively that there is jitter in the time retrieved from the time server. Let's also forget that for the moment. Say we poll the internet server and it says the time is exactly 12:00:00. Rounding to the seconds level just for simplicity, say my clock says 12:00:02, so I'm 2 seconds fast. So, we slow down the clock by tweaking its parameters. Then, we wait 16 more minutes. Now the time server says 12:16:00. Say my clock says 12:15:57. Now, I'm 3 seconds slow, so we speed the clock back up. Now, theoretically, just like my pendulum clock, I should be able to get the parameters dialed in so the clock keeps time. However, behind the scenes, the intrinsic operational speed changed. While I'm sure I'm butchering the internal technicalities, let's say the clock has a speed knob, and if we set the speed knob to a value of 100, the the clock will count exactly 1 second while exactly 1 second passes. If this stayed true, NTPD would eventually set the speed knob at 100 and everybody would be happy. But the intrinsic speed of the oscillator changed, so that now setting that knob at 100 now makes the clock think 1.03 seconds has passed when, in actuality, 1 second has passed. So the clock is running fast. So, NTPD dials the speed knob back to 97. But now, the oscillator has changed again so that a setting of 97 now makes the clock think that .95 seconds have passed, when, in actuality, 1 second has passed. This is why I'm getting such wild oscillation in the graph. No matter what NTPD does to tweak the clock speed, and no matter how accurate that is at the time, that adjustment never has the same effect the next time the time server is polled. Just as setting the screw on the pendulum of my mechanical clock doesn't have the same effect tomorrow as it does today. There will never be a setting that just works. I don't think it's a game you can win on a standard windows computer. So, I'm not even inclined to play the internet NTP server game. So, by polling my GPS every 8 seconds, the computer has much less time to drift, no
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David, I really appreciate all these suggestions you shared, as well as past ones. Based somewhat on been there, done that! If I decide to revamp my network, I'll probably put some of them into use. However, that's not really practical right now. All the networking gear is in the basement and all the PC's are upstairs. I've already spent 2 months working on this GPS stuff and ignoring some other things I need to be doing. I think I'm just going to focus on getting the Sure board up and running on a time server when it comes and, perhaps, use my BU-353 as a backup time source, and use the internet servers as a third level backup source. Most of the time, I won't care what they're doing Hopefully, I can spend less time thinking about time and just know that my PC's clocks are right. Regardless, I'm going to continue to have an interest in the topic and have enjoyed all the discussions and learning that have occurred. It's just that I have to do at least a few other things besides this. Sincerely, Ron Yes, sensitive those these new GPS receivers are, the basement may not be the best location!Be certain to get the Sure antenna in a good location - it's likely sealed for outdoor use such as stuck to a car roof. I do see quite a wide variation in performance over Wi-Fi - I have two permanent PCs (Molde and Puffin) and two temporary PCs (Bergen and Mercury) connected at the moment, and averaged jitter varies a lot: 1.0 - 4.3 ms - Molde 1.1 - 2.1 ms - Puffin 1.3 - 3 ms - Bergen 4 - 12 ms - Mercury http://www.satsignal.eu/mrtg/performance_ntp.php They are all synced to a Stratum-1 FreeBSD server showing microsecond jitter, running the same NTP, with the same configuration. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Loopstats update - how often?
If I have a configuration including: _ server 192.168.0.7 minpoll 5 maxpoll 5iburst server 0.uk.pool.ntp.org iburst minpoll 10 _ how often should the loopstats be updated? I was expecting something near to every 32 seconds, but it seems that sometimes it can be more than 64 seconds. Is that correct? Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Sure gps looses all sattelite fixes
"unruh" wrote in message news:wf78r.33384$kv1.26...@newsfe03.iad... [] Just wanted to report here. I switched the antennae on the two Sure GPS I have. Both worked fine for about 4 days, and suddenly the antenna that had failed before failed again-- no sattelites found. So, I am sure it is the antenna that is failing. Sure has said that they will send me a new one, but it has not arrived yet. I've had this happen with GPS antennas from UK suppliers as well. They are consumer level items, so the odd failure is not unknown. The supplier replaced the item without question, although they may wanted the failed unit back. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David T, NOW you understand. I have 4 PC's connected to the LAN, plus my wife's work computer 3 days / week, and on rare occasions my son's computer. All are connected by wifi. All do pretty mundane things: web browser, email, sometimes downloading patches, sometimes doing online backup. My 4 are running NTPD. 3 run windows most of the time and dual boot into linux. My 4th machine runs linux all the time. When my wife is here, she does a remote desktop type of thing into her work system. Two of my PC's are running Vista, one is running Windows 7. Those three dual boot into Ubuntu 11.04 and the always linux machine runs Ubuntu 11.04. Almost all the discussions I've had on this mailing list are for my Windows 7 machine. The path out of my house is: PC Wifi --> Wifi router --> wired router --> cable modem --> ISP -- internet - is this PC connected over wireless or wired? Wifi G - what else is going through the router? Someone else downloading large files or using streaming audio or video? See above. Normally, no huge data hogs. - who else might be sharing your connection? It's cable. Who knows? I also get cable TV and telephone through the same wire. - what type of service do you have? Presumably not dial-up! But what speed? Comcast Cable Just tested it with speedtest.net Ping to near city: 91 ms, Download: 29.63 Mbps, Upload: 5.3 Mbps - having checked you speed, would you describe your connection as "stable"? See above for speed. Generally, it's very stable. However, for the purposes we're discussing, I think it's latencies and delays that are the problem. As I mentioned in my reply to David L, I'm not concerned over trying to get stellar performance from internet servers. I just want to get a good GPS server system running and use the internet servers as a backup. Sincerely, Ron Ron, Thanks for that clarification. I think you should be getting /very much/ better performance from your Internet servers. That ping is poor as well. Here I have 30 Mb/s down, just 1 Mb/s up, and NTP delays show as 18-34 ms (most in 22-30 ms). To that end, if your cable modem has multiple ports, connect one of the PCs direct to the CM and run it as your local NTP server. Wi-Fi doesn't help NTP. Later, you can add GPS/PPS to that PC as well. At the very least, connect your timekeeping PC direct to the wired router. No Wi-Fi! For my main NTP server, I got a low-powered and fan-less Intel Atom system, and it runs FreeBSD. It /only/ runs NTP, no interactive stuff at all. You might also consider getting rid of the two routers and just using the wireless one. You might also see whether you can run NTP on your router - perhaps it's a model which can run the DD-WRT firmware. I think some variants of DD-WRT can run NTP, but please check. I have a WRT 54GL in my system where I run the DD-WRT firmware. http://www.dd-wrt.com/site/index Online backup could well affect the performance of the connection for timekeeping, and your imminent Sure GPS/PPS will help enormously. Just some thoughts which may help you along the way. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"unruh" wrote in message news:HI48r.39505$zd5.1...@newsfe12.iad... On 2012-03-14, David J Taylor <> wrote: [] Windows uses UTC internally, not local time. Local time is simply a presentation layer issue. Windows is unaffected by a DST transition. That must be new, since windows certainly used to maintain system time as local time. Caused numberous headaches for people using both Windows and Linux. Not new at all. It's been that way since 1992 for the whole of the NT family. Perhaps you are thinking of what is stored in the real-time clock chip? Windows and UNIX have different conventions for that, Windows using wall-clock time. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"Ron Frazier (NTP)" wrote in message news:4f60bc0c.8040...@c3energy.com... [] OK. Here are the loopstats from another computer for 7 days (in the chart). I don't have any peerstats for it. It has the same server list. One is preferred. All servers are active. Performance is no better. http://dl.dropbox.com/u/9879631/TAZ%20loopstats%202012-03-07%20to%202012-03-14.jpg http://dl.dropbox.com/u/9879631/ntp.conf-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120313-TAZ http://dl.dropbox.com/u/9879631/loopstats.20120314-TAZ Sincerely, Ron That's horrible, Ron! Much worse than David Lord reports. It makes me want to ask a number of questions: - is this PC connected over wireless or wired? - what else is going through the router? Someone else downloading large files or using streaming audio or video? - who else might be sharing your connection? - what type of service do you have? Presumably not dial-up! But what speed? - having checked you speed, would you describe your connection as "stable"? The quiet periods (e.g early Monday morning, Tuesday lunchtime) are much nearer to what I would hope for, which makes me wonder whether something is interfering with the connection outside those times. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] NTP, SNMP on FreeBSD 8.2
Folks, I'm interested to know whether my install of NTP on FreeBSD 8.2 includes SNMP support or not. If it doesn't, then I may try a recompile, but first: 1 - can anyone point me to the correct place to download the appropriate MIB? I did find: http://tools.ietf.org/html/draft-ietf-ntp-ntpv4-mib-07 but the MIB information is interspersed with page headers, and whilst I did try and edit it, I can't be sure it compiled, and hence a plain MIB would be preferable. I did look elsewhere but only found Meinberg and Cisco MIBs which could be proprietary. 2 - In the absence of a properly compiled MIB, can anyone point me to a numeric OID which should be visible if NTP/SNMP is running? Ideally, the OID corresponding to: ntpq "-c rv 0 offset" I can then use GetIF (or whatever) to look for that OID from my FreeBSD ssytem. Thanks, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Offset Average (Normal)?
"Alby VA" wrote in message news:ed7bfa7e-3754-43f0-bd72-0efc709cd...@s7g2000yqm.googlegroups.com... [] http://bugs.ntp.org/show_bug.cgi?id=2164 Thanks. I'm going to watch and see what comes of this bug. I agree, the ntpq output should be able to give you nanosecond precision vs. microsecond. I've not seen any reaction as yet. Maybe if it doesn't get approved for some reason you might want to chip in with support. It may also be that SNMP can report more accurate values directly, but when I last checked SNMP support wasn't yet in the Windows port (although Windows isn't yet accurate enough to need sub-microsecond precision!). I'll start a new thread about SNMP. Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
Hi David, OK. You asked for it. 8-) Well, I actually suggested /all/ the Internet servers being enabled, allowing NTP to make its best choice. When I'm through testing, I'll open up the other internet servers as a backup in case the GPS fails. For now, I'm just running with one clock source at a time. Still trying to document and chase down this wandering effect. I ran with NY NIST as the only selectable clock source and monitoring the GPS for comparison all night. The results were horrible. My offsets from NIST time were in the + 65 ms / - 75 ms range. I had the polling interval set to start at 1 minute and go up to 4 minutes. There is way too much clock wander to even think about testing the accuracy of the GPS. I've gone back to polling the GPS every 8 seconds as the sole selectable clock source and monitoring the internet servers for comparison. Over the short term, minutes to hours, my GPS, even with NMEA only, is by far the most accurate time source I have. Even if the NMEA signal wanders 70 ms either way over the course of a few days, it won't get any further off than I did using the internet server, and the clock will be much more consistent over shorter time frames. Here are the graphs. http://dl.dropbox.com/u/9879631/nynist01.jpg http://dl.dropbox.com/u/9879631/nynist02.jpg Sincerely, Ron I'm not surprised that using a single Internet server is worse than the GPS/USB, but that's not how NTP is designed to work. With two or more Internet servers active, your GPS 50-second glitch would not have affected your PC's timekeeping anything like as severely, when you have the GPS/USB included to help improve the offset and more like the narrow band (about 15 milliseconds wide) shown in: http://dl.dropbox.com/u/9879631/drifting01-peerstats.20120312.jpg Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Offset Average (Normal)?
"Alby VA" wrote in message news:0d4f588e-bab6-4706-826e-299149054...@i2g2000vbv.googlegroups.com... [] Thanks. That bug report sounds like the best plan of attack. Can that bug report be tracked to see if any action is taken? Yes, it's number 2164. See: http://bugs.ntp.org/show_bug.cgi?id=2164 Cheers, David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Offset Average (Normal)?
"Alby VA" wrote in message
news:2ece7b6a-e150-432d-b23a-a4bde46df...@j11g2000yqj.googlegroups.com...
[]
Hm, what do you think about this command for getting
loopstat data?
tail -n1 -r loopstats | awk '{print $3}'
tail -n1 -r loopstats = This looks at the last line of the loopstat
file
awk '{print $3}' === This pulls the data from the 3rd field which is
the offset info
Example:
--
godzilla# tail -n1 -r loopstats | awk '{print $3}'
0.02814
If you could code that into a perl script that MRTG uses, we'd be
golden.
To work over a network, I really need data which is available through the
standard ntpq command. You are welcome to find a Perl expert who could
coude that for your local PC, though.
I will raise a bug report for NTP about the precision of the data being
sometimes now marginal.
Cheers,
David
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Re: [ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.
"unruh" wrote in message news:I1T7r.36416$l12.35...@newsfe23.iad... [] Did you shut down and restart your computer? Did you perchance do this during the daylight savings time transition on a Windows system? Could the error be related to the fact that Windows like time on localtime not UTC? Windows uses UTC internally, not local time. Local time is simply a presentation layer issue. Windows is unaffected by a DST transition. David ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
