From: David Vernet <void@manifault.com>
To: Tejun Heo <tj@kernel.org>
Cc: peterz@infradead.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, mingo@redhat.com
Subject: Re: [PATCH 1/6] sched_ext: Simplify scx_can_stop_tick() invocation in sched_can_stop_tick()
Date: Mon, 5 Aug 2024 12:55:56 -0500 [thread overview]
Message-ID: <20240805175556.GC42857@maniforge> (raw)
In-Reply-To: <20240804024047.100355-2-tj@kernel.org>
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On Sat, Aug 03, 2024 at 04:40:08PM -1000, Tejun Heo wrote:
> The way sched_can_stop_tick() used scx_can_stop_tick() was rather confusing
> and the behavior wasn't ideal when SCX is enabled in partial mode. Simplify
> it so that:
>
> - scx_can_stop_tick() can say no if scx_enabled().
>
> - CFS tests rq->cfs.nr_running > 1 instead of rq->nr_running.
>
> This is easier to follow and leads to the correct answer whether SCX is
> disabled, enabled in partial mode or all tasks are switched to SCX.
>
> Peter, note that this is a bit different from your suggestion where
> sched_can_stop_tick() unconditionally returns scx_can_stop_tick() iff
> scx_switched_all(). The problem is that in partial mode, tick can be stopped
> when there is only one SCX task even if the BPF scheduler didn't ask and
> isn't ready for it.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David Vernet <void@manifault.com>
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next prev parent reply other threads:[~2024-08-05 17:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-04 2:40 [PATCHSET sched_ext/for-6.12] sched_ext: Misc updates Tejun Heo
2024-08-04 2:40 ` [PATCH 1/6] sched_ext: Simplify scx_can_stop_tick() invocation in sched_can_stop_tick() Tejun Heo
2024-08-05 17:55 ` David Vernet [this message]
2024-08-04 2:40 ` [PATCH 2/6] sched_ext: Add scx_enabled() test to @start_class promotion in put_prev_task_balance() Tejun Heo
2024-08-05 17:57 ` David Vernet
2024-08-04 2:40 ` [PATCH 3/6] sched_ext: Use update_curr_common() in update_curr_scx() Tejun Heo
2024-08-05 18:23 ` David Vernet
2024-08-04 2:40 ` [PATCH 4/6] sched_ext: Simplify UP support by enabling sched_class->balance() in UP Tejun Heo
2024-08-05 19:49 ` David Vernet
2024-08-04 2:40 ` [PATCH 5/6] sched_ext: Improve comment on idle_sched_class exception in scx_task_iter_next_locked() Tejun Heo
2024-08-05 19:50 ` David Vernet
2024-08-04 2:40 ` [PATCH 6/6] sched_ext: Make task_can_run_on_remote_rq() use common task_allowed_on_cpu() Tejun Heo
2024-08-05 19:55 ` David Vernet
2024-08-06 8:12 ` Peter Zijlstra
2024-08-06 17:04 ` Tejun Heo
2024-08-06 19:39 ` [PATCH v2 " Tejun Heo
2024-08-06 8:13 ` [PATCHSET sched_ext/for-6.12] sched_ext: Misc updates Peter Zijlstra
2024-08-06 19:39 ` Tejun Heo
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