linux-kernel - Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out

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Message-ID: <4E8DEFDE.4030706@zytor.com>
Date:	Thu, 06 Oct 2011 11:13:50 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jason Baron <jbaron@...hat.com>
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"David S. Miller" <davem@...emloft.net>,
	David Daney <david.daney@...ium.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Jan Glauber <jang@...ux.vnet.ibm.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Xen Devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	peterz@...radead.org, rth@...hat.com
Subject: Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized,
 don't nop it out

On 10/06/2011 11:10 AM, Jason Baron wrote:
> 
> It would be cool if we could make the total width 2-bytes, when
> possible.  It might be possible by making the initial 'JUMP_LABEL_INITIAL_NOP'
> as a 'jmp' to the 'l_yes' label. And then patching that with a no-op at boot
> time or link time - letting the compiler pick the width. In that way we could
> get the optimal width...
> 

Yes, that would be a win just based on icache footprint alone.

	-hpa

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

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