Messages in this thread | ![/](/images/icornerl.gif) | | From | Thomas Gleixner <> | Subject | Re: [PATCH clocksource 5/6] clocksource: Suspend the watchdog temporarily when high read latency detected | Date | Wed, 11 Jan 2023 12:26:58 +0100 |
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On Wed, Jan 04 2023 at 17:07, Paul E. McKenney wrote: > This can be reproduced by running memory intensive 'stream' tests, > or some of the stress-ng subcases such as 'ioport'. > > The reason for these issues is the when system is under heavy load, the > read latency of the clocksources can be very high. Even lightweight TSC > reads can show high latencies, and latencies are much worse for external > clocksources such as HPET or the APIC PM timer. These latencies can > result in false-positive clocksource-unstable determinations. > > Given that the clocksource watchdog is a continual diagnostic check with > frequency of twice a second, there is no need to rush it when the system > is under heavy load. Therefore, when high clocksource read latencies > are detected, suspend the watchdog timer for 5 minutes.
We should have enough heuristics in place by now to qualify the output of the clocksource watchdog as a random number generator, right?
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