linux-kernel - Re: [PATCH] jump_label: jump

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Message-ID: <20111201154036.GA2443@redhat.com>
Date:	Thu, 1 Dec 2011 10:40:36 -0500
From:	Jason Baron <jbaron@...hat.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	rostedt@...dmis.org
Subject: Re: [PATCH] jump_label: jump_label for boot options.

On Thu, Dec 01, 2011 at 11:53:53AM +0900, KAMEZAWA Hiroyuki wrote:
> I tried to use jump_label for handling memcg's boot options which sets
> global variable true/false and never changes after boot. And found jump_table
> is larger than expected. This patch is a trial to allow to place jump_table
> in .init section. How do you think ?
> 

Remeber too, that 'static_branch()' is inherently biased. That is, the
'false' path is assumed to be the the most likely path. Thus, the 'true'
path is move out-of-line. Thus, if the 'true' branch is potentially
used all the time, we would want to make sure that the savings of not
having to check a variable is still worth it. I should probably rename
static_branch() -> 'static_branch_default_false()' to make that clear.

Maybe we need an unbiased static_branch() too, but I'm not sure excatly
how to implement it...

Thanks,

-Jason
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