Messages in this thread | | | Date | Fri, 21 Mar 2008 23:09:32 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: 2.6.25-rc5-git6: Reported regressions from 2.6.24 |
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On Fri, 21 Mar 2008, Gabriel C wrote: > > So the rotating watchdog triggers for a yet to figure out reason. > > > > Oh, now that the pm timer seems to work again, can you try the following: > > > > apply the reverted patch again and let the box boot. At some point the > > TSC is marked unstable and is replaced by acpi_pm clocksource. > > > > What result does timewarp.c show in that situation ? > > Here it is , same kernel + Andi's patch : > > ./time-warp-test > 4 CPUs, running 4 parallel test-tasks. > checking for time-warps via: > - read time stamp counter (RDTSC) instruction (cycle resolution) > - gettimeofday (TOD) syscall (usec resolution) > - clock_gettime(CLOCK_MONOTONIC) syscall (nsec resolution) > > | 1.78 us, TSC-warps:0 | 19.27 us, TOD-warps:0 | 19.37 us, CLOCK-warps:0
Ok. So the watchdog trigger is a false positive.
Thinking more about it, it looks like Andi's change triggers some hidden bug in the combination of NO_HZ and add_timer_on(), where the CPU on which the timer is added is likely in a long idle sleep. I look into this tomorrow.
Thanks for testing
tglx
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