linux-kernel - Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags

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Message-ID: <84144f020904280215k6e2ae34dk8f1a14a51be2e203@mail.gmail.com>
Date:	Tue, 28 Apr 2009 12:15:41 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Wu Fengguang <fengguang.wu@...el.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Larry Woodman <lwoodman@...hat.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Matt Mackall <mpm@...enic.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags

Hi Andi,

On Tue, Apr 28, 2009 at 12:10 PM, Andi Kleen <andi@...stfloor.org> wrote:
>> Yes, zero overhead is important for certain things (like
>> CONFIG_SLUB_STATS, for example). However, putting slab allocator
>> specific checks in fs/proc looks pretty fragile to me. It would be nice
>
> Ok, perhaps that could be put into a inline into slab.h. Would
> that address your concerns?

Yeah, I'm fine with that. Putting them in the individual
slub_def.h/slob_def.h headers might be even better.

On Tue, Apr 28, 2009 at 12:10 PM, Andi Kleen <andi@...stfloor.org> wrote:
>> Also, while you probably don't want to use tracepoints for this kind of
>> instrumentation, you might want to look into reusing the ftrace
>> reporting bits.
>
> There's already perfectly fine code in tree for this, I don't see why it would
> need another infrastructure that doesn't really fit anyways.

It's just that I suspect that we want page flag printing and
zero-overhead statistics for kmemtrace at some point. But anyway, I'm
not objecting to extending /proc/kpageflags if that's what people want
to do.

                                          Pekka
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