Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [LKP] Re: [clocksource] 6c52b5f3cf: stress-ng.opcode.ops_per_sec -14.4% regression | Date | Fri, 23 Apr 2021 21:14:49 +0200 |
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On Thu, Apr 22 2021 at 07:24, Paul E. McKenney wrote: > On Thu, Apr 22, 2021 at 03:41:26PM +0800, Feng Tang wrote: > So what are our options? > > 1. Clear CLOCK_SOURCE_MUST_VERIFY from tsc-early. > > 2. #1, but add tsc-early into the watchdog list and set > CLOCK_SOURCE_MUST_VERIFY once it is better calibrated. > > 3. Add a field to struct clocksource that, if non-zero, gives > the maximum drift in nanoseconds per half second (AKA > WATCHDOG_INTERVAL). If zero, the WATCHDOG_MAX_SKEW value > is used. Set this to (say) 150,000ns for tsc-early. > > 4. As noted earlier, increase WATCHDOG_MAX_SKEW to 150 microseconds, > which again is not a good approach given the real-world needs > of real-world applications. > > 5. Your ideas here.
#3 or add a flag to the clocksource which says 'frequency is guesswork' and increase the threshold based on that.
If that flag is still set max_drift is != 0 after 20 seconds yell.
Thanks,
tglx
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