linux-kernel - Re: [PATCH 00/10] jump label: introduce very

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Message-ID: <4F450696.6010409@zytor.com>
Date:	Wed, 22 Feb 2012 07:15:34 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Ingo Molnar <mingo@...e.hu>, Jason Baron <jbaron@...hat.com>,
	a.p.zijlstra@...llo.nl, mathieu.desnoyers@...icios.com,
	davem@...emloft.net, ddaney.cavm@...il.com,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 00/10] jump label: introduce very_[un]likely + cleanups
 + docs

On 02/22/2012 07:12 AM, Steven Rostedt wrote:
> On Wed, 2012-02-22 at 15:56 +0100, Ingo Molnar wrote:
> 
>>> Because it really just looks like a stronger "unlikely()" and 
>>> fundamentally it really isn't. [...]
>>
>> Well, the fact is that right now it *is* a stronger unlikely() 
>> on architectures that have jump-labels and it's mapped to 
>> unlikely() on others.
>>
> 
> Has gcc been fix to make it truly an unlikely case and remove the "jmp;
> jmp" problem of before? I'm still using gcc 4.6.0 which has the
> following code for a tracepoint (example is the
> trace_sched_migrate_task().
> 

No, the jmp jmp problem still exists... I have discussed it with the gcc
folks and they have an idea for how to fix it, but I haven't even gotten
around to filing a formal RFE.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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