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Message-ID: <4C6816BD.8060101@redhat.com>
Date:	Sun, 15 Aug 2010 19:33:01 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christoph Hellwig <hch@....de>, Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Tom Zanussi <tzanussi@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Andi Kleen <andi@...stfloor.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, Tejun Heo <htejun@...il.com>
Subject: Re: [patch 1/2] x86_64 page fault NMI-safe

  On 08/11/2010 05:34 PM, Steven Rostedt wrote:
>
> So, I want to allocate a 10Meg buffer. I need to make sure the kernel
> has 10megs of memory available. If the memory is quite fragmented, then
> too bad, I lose out.

With memory compaction, the cpu churns for a while, then you have your 
buffer.  Of course there's still no guarantee, just a significantly 
higher probability of success.

> Oh wait, I could also use vmalloc. But then again, now I'm blasting
> valuable TLB entries for a tracing utility, thus making the tracer have
> a even bigger impact on the entire system.

Most trace entries will occupy much less than a page, and are accessed 
sequentially, so I don't think this will have a large impact.

-- 
error compiling committee.c: too many arguments to function

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