sched/core: Add ENQUEUE_RQ_SELECTED to indicate whether ->select_task_rq() was called

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During ttwu, ->select_task_rq() can be skipped if only one CPU is allowed or
migration is disabled. sched_ext schedulers may perform operations such as
direct dispatch from ->select_task_rq() path and it is useful for them to
know whether ->select_task_rq() was skipped in the ->enqueue_task() path.

Currently, sched_ext schedulers are using ENQUEUE_WAKEUP for this purpose
and end up assuming incorrectly that ->select_task_rq() was called for tasks
that are bound to a single CPU or migration disabled.

Make select_task_rq() indicate whether ->select_task_rq() was called by
setting WF_RQ_SELECTED in *wake_flags and make ttwu_do_activate() map that
to ENQUEUE_RQ_SELECTED for ->enqueue_task().

This will be used by sched_ext to fix ->select_task_rq() skip detection.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Vernet <void@manifault.com>

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This commit is contained in:

Tejun Heo 2024-09-27 13:46:12 -10:00

parent b62933eee4

commit f207dc2dcd

2 changed files with 9 additions and 2 deletions

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8

kernel/sched/core.c

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3

kernel/sched/sched.h

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