Messages in this thread | | | Date | Mon, 09 Mar 2009 21:42:37 +0100 | From | Jesper Krogh <> | Subject | Re: Linux 2.6.29-rc6 |
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john stultz wrote: > On Wed, 2009-03-04 at 18:39 -0800, john stultz wrote: >> On Wed, 2009-03-04 at 10:57 -0800, John Stultz wrote: >>> On Wed, 2009-03-04 at 19:36 +0100, Jesper Krogh wrote: >>>> jk@quad12:~$ python drift-test.py 10.192.96.19 >>>> 04 Mar 19:27:10 offset: -0.157696 drift: -693.0 ppm >>>> 04 Mar 19:28:10 offset: -0.195134 drift: -625.098360656 ppm >>>> 04 Mar 19:29:10 offset: -0.232579 drift: -624.595041322 ppm >>>> 04 Mar 19:30:10 offset: -0.270021 drift: -624.408839779 ppm >>>> 04 Mar 19:31:11 offset: -0.307461 drift: -621.727272727 ppm >>>> 04 Mar 19:32:11 offset: -0.344903 drift: -622.185430464 ppm >>>> 04 Mar 19:33:11 offset: -0.382345 drift: -622.491712707 ppm >>>> 04 Mar 19:34:11 offset: -0.419794 drift: -622.727488152 ppm >>>> 04 Mar 19:35:11 offset: -0.457239 drift: -622.89626556 ppm >>> >>> Yea, so from this and the settled ntpdc -c kerninfo data before, we can >>> see that the drift is further out then the 500ppm NTP can handle. >>> >>> So with that at least confirmed, we can focus back on to the fast-pit >>> tsc calibration code. >>> >>> Ingo, Thomas: I'm missing a bit of the context to that patch, other then >>> just speeding up boot times, was there other rational for moving away >>> from the ACPI PM timer based calibration? >>> >>> Could we maybe add a quick test that the pit reads actually take the >>> assumed 2us max? Doing this maybe via the HPET/ACPI PM? >> Hey Jesper, >> >> Here's a very-hackish patch to see if the approach I'm considering >> might fix the issue you're hitting. Could you apply it, boot the kernel >> a few times and send me the following segments of the dmesg for each of >> those boots (the example below is from my test box)? >> >> tsc delta: 44418024 >> ref_freq: 3000100 pit_freq: 3000384 >> TSC: Fast PIT calibration matches PMTIMER. >> TSC: PIT calibration matches PMTIMER. 1 loops >> Detected 3000.045 MHz processor.
Hi John.
Patched into 2.6.28.7 ..
First boot. [ 0.000000] tsc delta: 34203220 [ 0.000000] ref_freq: 2311825 pit_freq: 2310386 [ 0.000000] TSC: Fast PIT calibration matches PMTIMER. [ 0.000000] TSC: PIT calibration matches PMTIMER. 2 loops [ 0.000000] Detected 2311.877 MHz processor. Second boot: [ 0.000000] tsc delta: 34200313 [ 0.000000] ref_freq: 2311803 pit_freq: 2310190 [ 0.000000] TSC: Fast PIT calibration matches PMTIMER. [ 0.000000] TSC: PIT calibration matches PMTIMER. 2 loops [ 0.000000] Detected 2311.876 MHz processor. Third boot: [ 0.000000] tsc delta: 34198686 [ 0.000000] ref_freq: 2311824 pit_freq: 2310080 [ 0.000000] TSC: Fast PIT calibration matches PMTIMER. [ 0.000000] TSC: PIT calibration matches PMTIMER. 1 loops [ 0.000000] Detected 2311.872 MHz processor. Fourth boot: [ 0.000000] tsc delta: 34199433 [ 0.000000] ref_freq: 2311831 pit_freq: 2310130 [ 0.000000] TSC: Fast PIT calibration matches PMTIMER. [ 0.000000] TSC: PIT calibration matches PMTIMER. 2 loops [ 0.000000] Detected 2311.821 MHz processor.
-- Jesper
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