From: Tejun Heo <tj@kernel.org>
To: Tao Cui <cui.tao@linux.dev>
Cc: arighi@nvidia.com, void@manifault.com, changwoo@igalia.com,
michalblk@google.com, emil@etsalapatis.com,
sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org, cuitao@kylinos.cn
Subject: Re: [PATCH v2] sched_ext: don't deliver duplicate ops.cgroup_set_idle() for same value
Date: Wed, 02 Sep 2026 07:48:16 -1000 [thread overview]
Message-ID: <a8b5c606e0e52a93f8bee7e6d6a7f78c@kernel.org> (raw)
In-Reply-To: <20260901124347.755904-1-cui.tao@linux.dev>
> ops.cgroup_set_idle() is documented to be invoked when a cgroup
> transitions between idle and non-idle states, and scx_group_set_weight()
> already skips value-preserving writes. scx_group_set_idle() delivers
> every write unconditionally, so rewriting an already-correct cpu.idle
> value feeds the BPF scheduler a transition callback each time, which
> toggle- or accounting-based schedulers miscount. Mirror the weight
> guard and only deliver on an actual change.
Applied to sched_ext/for-7.3-fixes with the subject capitalized and the
new comparison changed to tg->scx.idle, which is the field's name there:
- tg->scx.sched_idle != idle)
+ tg->scx.idle != idle)
The rename to tg->scx.sched_idle is on for-7.4 and the for-next merge
switches the comparison back.
Thanks.
--
tejun
prev parent reply other threads:[~2026-09-02 17:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 12:43 Tao Cui
2026-09-02 17:48 ` Tejun Heo [this message]
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