On Thu, Aug 05, 2021 at 08:37:27AM -0700, Paul E. McKenney wrote: >On Thu, Aug 05, 2021 at 01:39:40PM +0800, Chao Gao wrote: >> [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@xxxxxxxxx> > >Very good, thank you! I will apply this on the next rebase. > >> >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. > >Whew! ;-) > >So about once per 13 clocksource watchdog checks. > >To Andi's point, do you have enough information in your console log to >work out the longest run of course-grained clocksource checks? Yes. 5 consecutive course-grained clocksource checks. Note that considering the reinitialization after course-grained check, in my calculation, two course-grained checks are considered consecutive if they happens in 1s(+/- 0.3s). Thanks Chao
