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Date: Thu, 7 Jul 2011 14:15:35 -0400
From: Jason Baron <jbaron@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>,
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        Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
        Pavel Emelyanov <xemul@openvz.org>, Hu Tao <hutao@cn.fujitsu.com>
Subject: Re: [patch 00/17] CFS Bandwidth Control v7.1
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On Thu, Jul 07, 2011 at 07:20:20PM +0200, Peter Zijlstra wrote:
> On Thu, 2011-07-07 at 12:23 -0400, Jason Baron wrote:
> 
> > yes, this is the type of case jump labels is designed for. Let me know
> > if there are any usage questions/concerns.
> 
> Unrelated to this change, I was looking at a case where it would be nice
> to have a way to specify the initial state of jump labels.
> 
> That is, currently:
> 
> jump_label_key foo;
> 
>   if (static_branch(&foo))
> 
> will default to false, until jump_label_inc(&foo) etc..
> 
> I was looking to add something like:
> 
> jump_label_key foo = JUMP_LABEL_TRUE;
> 
> Which would initialize the thing to be true, the problem with that is
> that it takes until the loop in jump_label_init() before that takes
> effect, which was too late in my particular case.
> 

We don't have to wait until jump_label_init() to make it take effect.

We could introduce something like: static_branch_default_false(&foo),
and static_branch_default_true(&foo), which are set at compile time. I
was waiting for a real world example before introducing it, but if this
would solve your issue,  we can look at it.

-Jason