From: Tejun Heo <tj@kernel.org>
To: Usama Arif <usama.arif@linux.dev>
Cc: arighi@nvidia.com, bpf@vger.kernel.org, bsegall@google.com,
changwoo@igalia.com, dietmar.eggemann@arm.com, etsal@meta.com,
juri.lelli@redhat.com, kprateek.nayak@amd.com,
linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com,
peterz@infradead.org, rostedt@goodmis.org,
sched-ext@lists.linux.dev, vincent.guittot@linaro.org,
void@manifault.com, vschneid@redhat.com, yphbchou0911@gmail.com
Subject: Re: [PATCH] sched_ext: Place dsq_vtime next to dsq_priq
Date: Thu, 24 Sep 2026 06:57:56 -1000 [thread overview]
Message-ID: <6ae9d2d1972afdedf0117ec01aba783f@kernel.org> (raw)
In-Reply-To: <20260924161446.3039726-1-usama.arif@linux.dev>
Hello,
On Thu, Sep 24, 2026 at 09:14:46AM -0700, Usama Arif wrote:
> scx_dispatch_enqueue() calls rb_add() for a vtime-ordered DSQ while
> holding dsq->lock. At each level of the descent, scx_dsq_priq_less()
> loads the visited task's dsq_vtime, and that comparison selects rb_left
> or rb_right from the same task's dsq_priq. In the x86-64 benchmark
> configuration, these accesses fell on different 64-byte cache lines
> before this change, so a cold visited task could require a second cache
> line fill on the dependent descent path.
Applied to sched_ext/for-7.4.
Thanks.
--
tejun
prev parent reply other threads:[~2026-09-24 16:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 16:14 [PATCH] sched_ext: Place dsq_vtime next to dsq_priq Usama Arif
2026-09-24 16:57 ` Tejun Heo [this message]
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