Re: [PATCH] clocksource: Add heuristics to avoid switching away from TSC due to timer delay

2018-12-04 Thread Roland Dreier
> /* > * Proper multiline comments look like this not like > * the above. > */ Got it, will fix next time around. > That aside. Why are you trying to do heuristics on the delta? > > We have way better information than that.

Re: [PATCH] clocksource: Add heuristics to avoid switching away from TSC due to timer delay

2018-12-04 Thread Thomas Gleixner
Roland, On Fri, 30 Nov 2018, Roland Dreier wrote: > delta = clocksource_delta(csnow, cs->cs_last, cs->mask); > + > + /* If the cycle delta is beyond what we can safely > + * convert to nsecs, and the watchdog clocksource > + * suggests that

[PATCH] clocksource: Add heuristics to avoid switching away from TSC due to timer delay

2018-11-30 Thread Roland Dreier
On a modern x86 system, the TSC is used as a clocksource, with HPET used in the clocksource watchdog to make sure that the TSC is stable. If the clocksource watchdog_timer is delayed for an extremely long time (for example if softirqs are being serviced in ksoftirqd, and realtime threads are