linux-kernel - Re: [PATCH] task_work: avoid unneeded cmpxchg() in task_work

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Message-ID: <1349780697.7880.14.camel@twins>
Date:	Tue, 09 Oct 2012 13:04:57 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Lai Jiangshan <laijs@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Ingo Molnar <mingo@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH] task_work: avoid unneeded cmpxchg() in task_work_run()

On Mon, 2012-10-08 at 14:38 +0200, Oleg Nesterov wrote:
> But the code looks more complex, and the only advantage is that
> non-exiting task does xchg() instead of cmpxchg(). Not sure this
> worth the trouble, in this case task_work_run() will likey run
> the callbacks (the caller checks ->task_works != NULL), I do not
> think this can add any noticeable speedup. 

Yeah, I agree, the patch doesn't seem worth the trouble. It makes tricky
code unreadable at best.

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