linux-kernel - Re: [PATCH 0/5] ftrace: to kill a daemon

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Message-ID: <alpine.LFD.1.10.0808081750060.3462@nehalem.linux-foundation.org>
Date:	Fri, 8 Aug 2008 17:51:16 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
cc:	Steven Rostedt <rostedt@...dmis.org>,
	Andi Kleen <andi@...stfloor.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	Roland McGrath <roland@...hat.com>,
	Ulrich Drepper <drepper@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Gregory Haskins <ghaskins@...ell.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	"Luis Claudio R. Goncalves" <lclaudio@...g.org>,
	Clark Williams <williams@...hat.com>
Subject: Re: [PATCH 0/5] ftrace: to kill a daemon



On Fri, 8 Aug 2008, Jeremy Fitzhardinge wrote:
>
> Steven Rostedt wrote:
> > I wish we had a true 5 byte nop. 
> 
> 0x66 0x66 0x66 0x66 0x90

I don't think so. Multiple redundant prefixes can be really expensive on 
some uarchs.

A no-op that isn't cheap isn't a no-op at all, it's a slow-op.

			Linus
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