Messages in this thread | | | Date | Sun, 25 Apr 2021 21:12:35 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH v10 clocksource 3/7] clocksource: Check per-CPU clock synchronization when marked unstable |
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On Sun, Apr 25, 2021 at 03:47:04PM -0700, Paul E. McKenney wrote: > Some sorts of per-CPU clock sources have a history of going out of > synchronization with each other. However, this problem has purportedy > been solved in the past ten years. Except that it is all too possible > that the problem has instead simply been made less likely, which might > mean that some of the occasional "Marking clocksource 'tsc' as unstable" > messages might be due to desynchronization. How would anyone know? > > Therefore apply CPU-to-CPU synchronization checking to newly unstable > clocksource that are marked with the new CLOCK_SOURCE_VERIFY_PERCPU flag. > Lists of desynchronized CPUs are printed, with the caveat that if it > is the reporting CPU that is itself desynchronized, it will appear that > all the other clocks are wrong. Just like in real life.
Well I could see this causing a gigantic flood of messages then. Assume I have 300 cores, do I get all those messages 300 times repeated then? If the console is slow this might end up taking a lot of CPU time.
And in a larger cluster this might not be uncommon.
There must be some way to throttle this.
-Andi
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