Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 9 Dec 2021 08:44:00 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] Clocksource: Avoid misjudgment of clocksource |
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On Thu, Dec 09, 2021 at 09:14:05PM +0800, Gang Li wrote: > Hi all, > > How about changing clocksource_watchdog from classical timer to hrtimer? > hrtimer is more accurate and stable, and makes it much easier for us to deal > with misjudgments.
To make hrtimer more accurate in the busy-system scenarios that are under test, we would need to specify HRTIMER_MODE_HARD. Otherwise, hrtimer handlers execute in softirq, just like timers do. So without the HRTIMER_MODE_HARD, the hrtimers would be delayed just as badly as we are seeing for the normal timers.
Unfortunately, use of HRTIMER_MODE_HARD has response-time consequences, especially when the timer reads need to be retried. So my guess is that hrtimers are not a helpful path forward here.
Thanx, Paul
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