linux-kernel - Re: [PATCH 0/3] Use jump_label for sched

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Message-ID: <1323198720.32012.84.camel@twins>
Date:	Tue, 06 Dec 2011 20:12:00 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Jason Baron <jbaron@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Mike Galbraith <efault@....de>, Paul Turner <pjt@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [PATCH 0/3] Use jump_label for sched_feat()

On Tue, 2011-12-06 at 13:10 -0500, Jason Baron wrote:
> On Tue, Dec 06, 2011 at 06:15:34PM +0100, Peter Zijlstra wrote:
> > These patches implement sched_feat() using jump_labels. The first is a section
> > mismatch fix. The second patch provides a little infrastructure and the third
> > patch applies it to make sched_feat() use static_branch().
> > 
> > It uses static_branch() coupled with unlikely/likely in order to control the
> > branch block position. I haven't checked if it works, but it likely doesn't,
> > although it should.
> > 
> > 
> 
> It doesn't. I played around with unlikely/likely a bit, and it
> didn't seem to make a difference. 

Right, we should look at getting that fixed though.. I think its a very
useful hint to have.

> That said, jump_labels could still be
> an improvement here - it be good if we had some numbers, I guess.

Yeah, acme had some number on an older version of this patch.
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