Messages in this thread | | | Date | Thu, 12 Nov 2020 12:38:54 +0000 | From | Quentin Perret <> | Subject | Re: [PATCH] sched/fair: Fix overutilized update in enqueue_task_fair() |
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On Thursday 12 Nov 2020 at 12:29:59 (+0000), Valentin Schneider wrote: > Alternatively: how much does not updating the overutilized status here help > us? The next tick will unconditionally update it, which for arm64 is > anywhere in the next ]0, 4]ms. That "fake" fork-time util_avg should already > be accounted in the rq util_avg, and even if the new task was running the > entire time, 4ms doesn't buy us much decay.
Yes, this is arguably a dodgy hack, which will not save us in a number of cases. The only situation where this helps is for short-lived tasks that will run only once. And this is a sadly common programming pattern.
So yeah, this is not the prettiest thing in the world, but it doesn't cost us much and helps some real-world workloads, so ...
Thanks, Quentin
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