Re: What does --disable-kernel-PLL do?

2017-04-24 Thread Eric S. Raymond
Responding to very old mail, from December... Hal Murray : > > > Here's the inside view from looking at the code: --disable-kernel-PLL turns > > off the use of ntp_adjtime() to slew time, leaving adjustments to be done at > > much coarser granularity by the old-style

Re: What does --disable-kernel-PLL do?

2016-12-02 Thread Gary E. Miller
Yo Hal! On Thu, 01 Dec 2016 23:29:23 -0800 Hal Murray wrote: > >> There is a tangle in this area that I don't understand. When ntpd > >> exits (or crashes), it leaves the previous state in the kernel so > >> anybody running ntptime will think things are fine. > > > What previous state? >

Re: What does --disable-kernel-PLL do?

2016-12-01 Thread Hal Murray
> Here's the inside view from looking at the code: --disable-kernel-PLL turns > off the use of ntp_adjtime() to slew time, leaving adjustments to be done at > much coarser granularity by the old-style adjtime(2) call. How about we rename it to --disable-ntp_adjtime? I assume w

Re: What does --disable-kernel-PLL do?

2016-12-01 Thread Eric S. Raymond
us, estimated error 1600 us, > status 0x40 (UNSYNC), > time constant 2, precision 1.000 us, tolerance 500 ppm, > > The long story is that I had a setup that included --disable-kernel-PLL. (I > don't remember why I added that.) I noticed that my daemon that records &g

What does --disable-kernel-PLL do?

2016-11-21 Thread Hal Murray
ant 2, precision 1.000 us, tolerance 500 ppm, The long story is that I had a setup that included --disable-kernel-PLL. (I don't remember why I added that.) I noticed that my daemon that records things like CPU and disk temperature and NTP's drift was getting 0 for the drift because that

✘24 hour data for --disable-kernel-pll

2016-09-29 Thread Gary E. Miller
Yo All! Below are the 24 hour results for --disable-kernel-pll on a RasPi 3 with Uputronics HAT. With --disable-kernel-pll Local Clock Local Clock Local ClockPPS PPS Poll Freq Offset 90% Jitter 90% Stability 90% Offset 90% Jitter 90% 1 1.36 ppm

Re: ✘--disable-kernel-pll

2016-09-29 Thread Gary E. Miller
Yo Daniel! On Thu, 29 Sep 2016 14:34:08 -0400 Daniel Franke wrote: > On Sep 29, 2016 2:23 PM, "Gary E. Miller" wrote: > > > Then maybe a worth while experimment to copy the kernel PLL into > > ntpd to see how it works there? > > I can't conceive of how you'd do that. It's too tightly integr

Re: ✘--disable-kernel-pll

2016-09-29 Thread Daniel Franke
On Sep 29, 2016 2:23 PM, "Gary E. Miller" wrote: > Then maybe a worth while experimment to copy the kernel PLL into ntpd > to see how it works there? I can't conceive of how you'd do that. It's too tightly integrated with the rest of the kernel timing subsystem and other internal kernel APIs. __

Re: ✘--disable-kernel-pll

2016-09-29 Thread Gary E. Miller
Yo Daniel! On Thu, 29 Sep 2016 10:06:01 -0400 Daniel Franke wrote: > On 9/28/16, Gary E. Miller wrote: > > The knerel PLL and the ntpd userspace PLL are supposed to be using > > the same algorithm and constants. Might be worth checking if the > > constants are still the same. > > They aren'

Re: ✘--disable-kernel-pll

2016-09-29 Thread Daniel Franke
On 9/28/16, Gary E. Miller wrote: > The knerel PLL and the ntpd userspace PLL are supposed to be using the > same algorithm and constants. Might be worth checking if the constants > are still the same. They aren't. In ntp_loopfilter.c, we have #define CLOCK_PLL 16. /* PLL loop gain (l

✘--disable-kernel-pll

2016-09-28 Thread Gary E. Miller
Yo All! I just ran a 6 hour test of --disable-kernel-pll. See attached. The left side before 18:45 is yesterday's ntpd. After that time is today's ntpd with --disable-kernel-pll. Nothing else changed. As the png shows, the frequency jitter declined, but the offset jitter increas