Messages in this thread | | | Date | Wed, 12 Apr 2023 19:53:05 +0800 | From | Aaron Lu <> | Subject | Re: [RFC PATCH] sched: Rate limit migrations |
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On Tue, Apr 11, 2023 at 05:41:16PM -0400, Mathieu Desnoyers wrote: > This WIP patch rate-limits migrations to 32 migrations per 10ms window > for each task. > > The specific migration count and window size can be changed with the > following defines in kernel/sched/sched.h: > > - SCHED_MIGRATION_WINDOW_NS > - SCHED_MIGRATION_LIMIT > > Testing is welcome, especially to see if it helps with Aaron's > migration-heavy workload wrt rseq concurrency id performance > regression.
Initial test shows the migration number for a 5s window is still in some millions and profile wise, contention didn't change much, still in the range of single digit to 20% something during 3 minutes run.
If this limit works, then the total migration number should be less than: 224 * 2 * 3200 * 5 = 7million so hard to say if the limit works as expected since the number I captured is indeed less than 7 million. 224 * 2 means totally there are 448 tasks, 224 client and 224 server. 3200 is the theoretical migration number for a task in a 1s window and 5 means 5 seconds.
I'll play with it more to see how things change.
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