Messages in this thread | | | Date | Thu, 5 Aug 2021 13:39:40 +0800 | From | Chao Gao <> | Subject | Re: [clocksource] 8901ecc231: stress-ng.lockbus.ops_per_sec -9.5% regression |
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[snip] >> This patch works well; no false-positive (marking TSC unstable) in a >> 10hr stress test. > >Very good, thank you! May I add your Tested-by?
sure. Tested-by: Chao Gao <chao.gao@intel.com>
> >I expect that I will need to modify the patch a bit more to check for >a system where it is -never- able to get a good fine-grained read from >the clock.
Agreed.
>And it might be that your test run ended up in that state.
Not that case judging from kernel logs. Coarse-grained check happened 6475 times in 43k seconds (by grep "coarse-grained skew check" in kernel logs). So, still many checks were fine-grained.
> >My current thought is that if more than (say) 100 consecutive attempts >to read the clocksource get hit with excessive delays, it is time to at >least do a WARN_ON(), and maybe also time to disable the clocksource >due to skew. The reason is that if reading the clocksource -always- >sees excessive delays, perhaps the clock driver or hardware is to blame. > >Thoughts?
It makes sense to me.
Thanks Chao
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