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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com>
Date:	Tue, 28 Apr 2009 12:19:50 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andi Kleen <andi@...stfloor.org>,
	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 Ingo,

On Tue, 2009-04-28 at 09:40 +0200, Andi Kleen wrote:
>> > > I think i have to NAK this kind of ad-hoc instrumentation of kernel
>> > > internals and statistics until we clear up why such instrumentation

* Pekka Enberg <penberg@...helsinki.fi> wrote:
>> > I think because it has zero fast path overhead and can be used
>> > any time without enabling anything special.

On Tue, Apr 28, 2009 at 12:15 PM, Ingo Molnar <mingo@...e.hu> wrote:
> ( That's a dubious claim in any case - tracepoints are very cheap.
>  And they could be made even cheaper and such efforts would benefit
>  all the tracepoint users so it's a prime focus of interest.
>  Andi is a SystemTap proponent, right? I saw him oppose pretty much
>  everything built-in kernel tracing related. I consider that a
>  pretty extreme position. )

I have no idea how expensive tracepoints are but I suspect they don't
make too much sense for this particular scenario. After all, kmemtrace
is mainly interested in _allocation patterns_ whereas this patch seems
to be more interested in "memory layout" type of things.

                                                Pekka
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/