Am 26.01.2014 um 17:28 schrieb Peter C. Wallace <[email protected]>: > On Sun, 26 Jan 2014, Michael Haberler wrote: > >> Date: Sun, 26 Jan 2014 09:59:52 +0100 >> From: Michael Haberler <[email protected]> >> To: EMC developers <[email protected]> >> Subject: Re: [Emc-developers] reports on rt-preempt / latency-test: max >> jitter >> going down >> could the folks observing this behaviour please run the following commands >> on their systems: >> >> cat /sys/devices/system/clocksource/clocksource0/available_clocksource >> >> cat /sys/devices/system/clocksource/clocksource0/current_clocksource >> >> background: Answer 2 of: >> http://stackoverflow.com/questions/5930621/problem-of-understanding-clock-gettime >> >> thanks! > > > cat /sys/devices/system/clocksource/clocksource0/available_clocksource > tsc acpi_pm > > cat /sys/devices/system/clocksource/clocksource0/current_clocksource > tsc
hm, I would have expected to find 'hpet' there (see also link below) maybe for some reason HPET isnt enabled in the kernel so not settable (is that by chance my howegrown 3.1x-mah rt-preempt kernel..?) > > > I changed the clocksource to acpi_pm but the error remains acpi_pm is probably the worst of all in terms of resolution, 3.58Mhz: http://stackoverflow.com/questions/7987671/what-is-the-acpi-pm-linux-clocksource-used-for-what-hardware-implements-it it's probably a good idea to figure out the best clock source, and make sure in the startup phase it's actually selected (assuming this is related at all) > One interesting thing is that the error is periodic with a ~4 second period > (like an uncaught 32 bit ns count wrap) hm, thats an interesting observation. Need to read the timedelta and rtapi_time code once more to see if there's something smelly. does that 4 second period show up with either clock source just alike? if so, this would suggest the clock source not be the cause I should be next to real hardware soon thanks! - Michael > > > > >> >> - Michael >> >> >> Am 25.01.2014 um 17:03 schrieb Michael Haberler <[email protected]>: >> >>> >>> Peter Wallace kindly help to locate the error, it is rtapi_get_time() going >>> backwards occasionally on rt-preempt, suggesting the cause is this function: >>> >>> >>> https://github.com/mhaberler/linuxcnc/blob/e3de5bb74857bbd9935c1a1d1f031a0558ca0f85/src/rtapi/rtapi_time.c#L166 >>> >>> this cause the 'del' variable in >>> https://github.com/mhaberler/linuxcnc/blob/e3de5bb74857bbd9935c1a1d1f031a0558ca0f85/src/hal/components/timedelta.comp >>> to become negative at times, causing the decreasing jitter >>> >>> no fix yet, but we know where to look >>> >>> -m >>> >>> >>> Am 25.01.2014 um 08:43 schrieb Michael Haberler <[email protected]>: >>> >>>> Reading back on IRC I found hints at rt-preempt ubc3 builds showing the >>>> max latency going down occasionally. >>>> >>>> Please: >>>> >>>> 1. report the exact kernel version, in particular if this is stock debian >>>> rt-preempt kernel. >>>> 2. check if ntp is running or not, i.e. the output of 'ps ax|grep ntp' >>>> 3. If yes, please stop the ntp demon with 'sudo /etc/init.d/ntp stop' or >>>> equivalent >>>> 4. Re-run latency-test after ntp is stopped. Does the problem reoccur? >>>> 5. Please report your results using the ubc issue tracker as mentioned >>>> here >>>> http://static.mah.priv.at/public/html/common/UnifiedBuild.html#_issue_tracker >>>> , for this issue: https://github.com/zultron/linuxcnc/issues/72 >>>> >>>> background: there is a chance that the issue is related to the behavior >>>> described here, in particular the subtle difference between >>>> CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW: >>>> >>>> http://stackoverflow.com/questions/3657289/linux-clock-gettimeclock-monotonic-strange-non-monotonic-behavior >>>> http://markmail.org/thread/54bb663vi47kjxnu >>>> >>>> - Michael >>>> >>>> >>>> >>>> ------------------------------------------------------------------------------ >>>> CenturyLink Cloud: The Leader in Enterprise Cloud Services. >>>> Learn Why More Businesses Are Choosing CenturyLink Cloud For >>>> Critical Workloads, Development Environments & Everything In Between. >>>> Get a Quote or Start a Free Trial Today. >>>> http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk >>>> _______________________________________________ >>>> Emc-developers mailing list >>>> [email protected] >>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>> >>> >>> ------------------------------------------------------------------------------ >>> CenturyLink Cloud: The Leader in Enterprise Cloud Services. >>> Learn Why More Businesses Are Choosing CenturyLink Cloud For >>> Critical Workloads, Development Environments & Everything In Between. >>> Get a Quote or Start a Free Trial Today. >>> http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk >>> _______________________________________________ >>> Emc-developers mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/emc-developers >> > > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
