linux-kernel - Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5

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Message-ID: <4E98AF71.40303@zytor.com>
Date:	Fri, 14 Oct 2011 14:53:53 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Jeremy Fitzhardinge <jeremy@...p.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>,
	Jason Baron <jbaron@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Xen Devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMIC
 instead of jmp5 +0

On 10/13/2011 11:37 AM, Steven Rostedt wrote:
> On Thu, 2011-10-13 at 09:57 -0700, Jeremy Fitzhardinge wrote:
>> On 10/13/2011 08:40 AM, H. Peter Anvin wrote:
>>> On 10/12/2011 05:08 PM, Jeremy Fitzhardinge wrote:
>>>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
>>>>
>>>> GENERIC_NOP5_ATOMIC should make a better nop.
>>>>
>>> On 32 bits, yes.  On 64 bits you should use P6_NOP5_ATOMIC.
>>
>> Something like this?
>>
> 
> No, we only care about 5byte nops here. Look at ideal_nop in
> alterative.c
> 

He needs a compile-time alternative.

	-hpa

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