cool - thanks for finding that. Sorry I could not test - nothing setup here - but I can test the fix monday.
sam On 01/26/2014 02:07 PM, Michael Haberler wrote: > I have a fix which works for me: > https://github.com/mhaberler/linuxcnc/commit/10924b5509a2d2e38533a9f9e876d139a2cf5d4b > (branch unified-build-candidate-3) > > I'd appreciate reports - this should repair the "latency-test: jitter going > down" error > > NB: this error did show only on i386 kernels, not on x86_64 > > the clocksource was not involved > > - Michael > > Am 26.01.2014 um 18:02 schrieb Peter C. Wallace <[email protected]>: > >> On Sun, 26 Jan 2014, Michael Haberler wrote: >> >>> Date: Sun, 26 Jan 2014 17:40:19 +0100 >>> From: Michael Haberler <[email protected]> >>> To: Peter C. Wallace <[email protected]>, >>> EMC developers <[email protected]> >>> Subject: Re: [Emc-developers] reports on rt-preempt / latency-test: max >>> jitter >>> going down >>> >>> 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..?) >> Yes >> >>> >>>> >>>> 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 >> >> >> Yes, same ~4 second period with either clock source, I HAL 'scoped >> the baddelta staircase and its 4.3 seconds as you would expect with a >> uncaught 32 bit wrap >> >>> 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. >> 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 > ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. 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