From: Tejun Heo <tj@kernel.org>
To: Kuba Piecuch <jpiecuch@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
David Vernet <void@manifault.com>,
Andrea Righi <arighi@nvidia.com>,
Changwoo Min <changwoo@igalia.com>,
sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] sched/core: Preserve WF_RQ_SELECTED across queued wakeups
Date: Fri, 23 Oct 2026 09:35:50 -1000 [thread overview]
Message-ID: <bba1b0e8d484f3da05cd956fb8052705@kernel.org> (raw)
In-Reply-To: <20261023144811.2230393-2-jpiecuch@google.com>
On Fri, Oct 23, 2026 at 02:48:04PM +0000, Kuba Piecuch wrote:
> ENQUEUE_RQ_SELECTED tells a sched_class that ->select_task_rq() was
> called for a task wakeup. sched_ext exposes this flag to BPF schedulers
> as SCX_ENQ_CPU_SELECTED. However, the flag is lost for queued wakeups,
> which a BPF scheduler can opt into with SCX_OPS_ALLOW_QUEUED_WAKEUP.
> This also results in undercounting SCX_EV_SELECT_CPU_FALLBACK events.
>
> Preserve WF_RQ_SELECTED for queued wakeups in the same way WF_MIGRATED
> is. This way, ttwu_activate() receives WF_RQ_SELECTED for queued wakeups
> and passes ENQUEUE_RQ_SELECTED to activate_task().
>
> Fixes: 3539c6411a7c ("sched_ext: Implement SCX_OPS_ALLOW_QUEUED_WAKEUP")
> Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
next prev parent reply other threads:[~2026-10-23 19:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-23 14:48 [PATCH 0/2] sched: Fix SCX_ENQ_CPU_SELECTED for queued wakeups Kuba Piecuch
2026-10-23 14:48 ` [PATCH 1/2] sched/core: Preserve WF_RQ_SELECTED across " Kuba Piecuch
2026-10-23 19:35 ` Tejun Heo [this message]
2026-10-23 20:12 ` Andrea Righi
2026-10-23 14:48 ` [PATCH 2/2] selftests/sched_ext: Test SCX_ENQ_CPU_SELECTED with " Kuba Piecuch
2026-10-23 15:12 ` sashiko-bot
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