linux-kernel - Re: [PATCH 3/3] sched_ext: Allow scx_bpf_reenqueue

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Message-ID: <aP-3QsygWJRn6Z2u@slm.duckdns.org>
Date: Mon, 27 Oct 2025 08:17:38 -1000
From: Tejun Heo <tj@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: David Vernet <void@...ifault.com>,
	Andrea Righi <andrea.righi@...ux.dev>,
	Changwoo Min <changwoo@...lia.com>, linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev, Wen-Fang Liu <liuwenfang@...or.com>
Subject: Re: [PATCH 3/3] sched_ext: Allow scx_bpf_reenqueue_local() to be
 called from anywhere

Hello,

On Mon, Oct 27, 2025 at 07:10:28PM +0100, Peter Zijlstra wrote:
...
> Just for my elucidation and such.. This is when ttwu() happens and the
> CPU is idle and you dispatch directly to it, expecting it to then go run
> that task. After which another wakeup/balance movement happens which
> places/moves a task from a higher priority class to that CPU, such that
> your initial (ext) task doesn't get to run after all. Right?

Yes, that's the scenario that I was thinking.

Thanks.

-- 
tejun