Messages in this thread | | | Date | Thu, 1 Sep 2022 17:59:11 +0800 | Subject | Re: [PATCH] sched/core: Fix the bug that sched_core_find() may return throttled task | From | cruzzhao <> |
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在 2022/9/1 下午5:02, Peter Zijlstra 写道: > On Wed, Aug 31, 2022 at 02:49:18PM +0800, Cruz Zhao wrote: >> When a cfs_rq is throttled, the cookie'd task in this cfs_rq wouldn't >> dequeue from the core tree, and sched_core_find() may return this task, >> which will result that the throttled task running on the cpu. >> >> To resolve this problem, we pick the first cookie matched task and >> unthrottled task. > > You mean: first that that both matches the cookie and is not throttled. >
Yeah, I mean "the first cookie matched and not throttled task".
> Except I think you can have the same problem with the RT crud.
Sure, there's the same problem with the RT crud.
There's also a problem that the priority of the tasks in the core_tree won't change since sched_core_enqueue(), but the priority of cfs tasks will change as vruntime changes. And sched_core_find() may not pick the cookie matched task with the highest priority.
I tried to combine the core_tree with cfs_rq (dl_rq, rt_rq should also be considered) to solve this problem, but I haven't come up with a simple and graceful solution yet.
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