[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> > >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
