From: Pekka Enberg <penberg@cs.helsinki.fi> To: Ingo Molnar <mingo@elte.hu> Cc: "Andi Kleen" <andi@firstfloor.org>, "Wu Fengguang" <fengguang.wu@intel.com>, "Steven Rostedt" <rostedt@goodmis.org>, "Frédéric Weisbecker" <fweisbec@gmail.com>, "Larry Woodman" <lwoodman@redhat.com>, "Peter Zijlstra" <a.p.zijlstra@chello.nl>, "Eduard - Gabriel Munteanu" <eduard.munteanu@linux360.ro>, "Andrew Morton" <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>, "Matt Mackall" <mpm@selenic.com>, "Alexey Dobriyan" <adobriyan@gmail.com>, "linux-mm@kvack.org" <linux-mm@kvack.org> Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags Date: Tue, 28 Apr 2009 12:25:06 +0300 [thread overview] Message-ID: <84144f020904280225h490ef682p8973cb1241a1f3ea@mail.gmail.com> (raw) In-Reply-To: <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com> 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@cs.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@elte.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. ) On Tue, Apr 28, 2009 at 12:19 PM, Pekka Enberg <penberg@cs.helsinki.fi> wrote: > 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. That said, I do foresee a need to be able to turn on more detailed tracing after you've identified problematic areas from kpageflags type of overview report. And for that, you almost certainly want kmemtrace/tracepoints style solution with pid/function/whatever regexp matching ftrace already provides. Pekka
WARNING: multiple messages have this Message-ID (diff)
From: Pekka Enberg <penberg@cs.helsinki.fi> To: Ingo Molnar <mingo@elte.hu> Cc: "Andi Kleen" <andi@firstfloor.org>, "Wu Fengguang" <fengguang.wu@intel.com>, "Steven Rostedt" <rostedt@goodmis.org>, "Frédéric Weisbecker" <fweisbec@gmail.com>, "Larry Woodman" <lwoodman@redhat.com>, "Peter Zijlstra" <a.p.zijlstra@chello.nl>, "Eduard - Gabriel Munteanu" <eduard.munteanu@linux360.ro>, "Andrew Morton" <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>, "Matt Mackall" <mpm@selenic.com>, "Alexey Dobriyan" <adobriyan@gmail.com>, "linux-mm@kvack.org" <linux-mm@kvack.org> Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags Date: Tue, 28 Apr 2009 12:25:06 +0300 [thread overview] Message-ID: <84144f020904280225h490ef682p8973cb1241a1f3ea@mail.gmail.com> (raw) In-Reply-To: <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com> 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@cs.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@elte.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. ) On Tue, Apr 28, 2009 at 12:19 PM, Pekka Enberg <penberg@cs.helsinki.fi> wrote: > 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. That said, I do foresee a need to be able to turn on more detailed tracing after you've identified problematic areas from kpageflags type of overview report. And for that, you almost certainly want kmemtrace/tracepoints style solution with pid/function/whatever regexp matching ftrace already provides. Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2009-04-28 9:25 UTC|newest] Thread overview: 137+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-04-28 1:09 [PATCH 0/5] proc: export more page flags in /proc/kpageflags (take 4) Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 1:09 ` [PATCH 1/5] pagemap: document clarifications Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 7:11 ` Tommi Rantala 2009-04-28 7:11 ` Tommi Rantala 2009-04-28 1:09 ` [PATCH 2/5] pagemap: documentation 9 more exported page flags Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 1:09 ` [PATCH 3/5] mm: introduce PageHuge() for testing huge/gigantic pages Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 1:09 ` [PATCH 4/5] proc: kpagecount/kpageflags code cleanup Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 1:09 ` [PATCH 5/5] proc: export more page flags in /proc/kpageflags Wu Fengguang 2009-04-28 1:09 ` Wu Fengguang 2009-04-28 6:55 ` Ingo Molnar 2009-04-28 6:55 ` Ingo Molnar 2009-04-28 7:40 ` Andi Kleen 2009-04-28 7:40 ` Andi Kleen 2009-04-28 9:04 ` Pekka Enberg 2009-04-28 9:04 ` Pekka Enberg 2009-04-28 9:10 ` Andi Kleen 2009-04-28 9:10 ` Andi Kleen 2009-04-28 9:15 ` Pekka Enberg 2009-04-28 9:15 ` Pekka Enberg 2009-04-28 9:15 ` Ingo Molnar 2009-04-28 9:15 ` Ingo Molnar 2009-04-28 9:19 ` Pekka Enberg 2009-04-28 9:19 ` Pekka Enberg 2009-04-28 9:25 ` Pekka Enberg [this message] 2009-04-28 9:25 ` Pekka Enberg 2009-04-28 9:36 ` Wu Fengguang 2009-04-28 9:36 ` Wu Fengguang 2009-04-28 9:36 ` Ingo Molnar 2009-04-28 9:36 ` Ingo Molnar 2009-04-28 9:57 ` Pekka Enberg 2009-04-28 9:57 ` Pekka Enberg 2009-04-28 10:10 ` KOSAKI Motohiro 2009-04-28 10:10 ` KOSAKI Motohiro 2009-04-28 10:21 ` Pekka Enberg 2009-04-28 10:21 ` Pekka Enberg 2009-04-28 10:56 ` Ingo Molnar 2009-04-28 10:56 ` Ingo Molnar 2009-04-28 11:09 ` KOSAKI Motohiro 2009-04-28 11:09 ` KOSAKI Motohiro 2009-04-28 12:42 ` Ingo Molnar 2009-04-28 12:42 ` Ingo Molnar 2009-04-28 11:03 ` Ingo Molnar 2009-04-28 11:03 ` Ingo Molnar 2009-04-28 17:42 ` Matt Mackall 2009-04-28 17:42 ` Matt Mackall 2009-04-28 9:29 ` Ingo Molnar 2009-04-28 9:29 ` Ingo Molnar 2009-04-28 9:34 ` KOSAKI Motohiro 2009-04-28 9:34 ` KOSAKI Motohiro 2009-04-28 9:38 ` Ingo Molnar 2009-04-28 9:38 ` Ingo Molnar 2009-04-28 9:55 ` Wu Fengguang 2009-04-28 9:55 ` Wu Fengguang 2009-04-28 10:11 ` KOSAKI Motohiro 2009-04-28 10:11 ` KOSAKI Motohiro 2009-04-28 11:05 ` Ingo Molnar 2009-04-28 11:05 ` Ingo Molnar 2009-04-28 11:36 ` Wu Fengguang 2009-04-28 11:36 ` Wu Fengguang 2009-04-28 12:17 ` [rfc] object collection tracing (was: [PATCH 5/5] proc: export more page flags in /proc/kpageflags) Ingo Molnar 2009-04-28 12:17 ` Ingo Molnar 2009-04-28 13:31 ` Wu Fengguang 2009-04-28 13:31 ` Wu Fengguang 2009-05-12 13:01 ` Frederic Weisbecker 2009-05-12 13:01 ` Frederic Weisbecker 2009-05-17 13:36 ` Wu Fengguang 2009-05-17 13:55 ` Frederic Weisbecker 2009-05-17 13:55 ` Frederic Weisbecker 2009-05-17 14:12 ` Wu Fengguang 2009-05-17 14:12 ` Wu Fengguang 2009-05-18 11:44 ` KOSAKI Motohiro 2009-05-18 11:44 ` KOSAKI Motohiro 2009-05-18 11:47 ` Wu Fengguang 2009-05-18 11:47 ` Wu Fengguang 2009-04-28 10:18 ` [PATCH 5/5] proc: export more page flags in /proc/kpageflags Andi Kleen 2009-04-28 10:18 ` Andi Kleen 2009-04-28 8:33 ` Wu Fengguang 2009-04-28 8:33 ` Wu Fengguang 2009-04-28 9:24 ` Ingo Molnar 2009-04-28 9:24 ` Ingo Molnar 2009-04-28 18:11 ` Tony Luck 2009-04-28 18:11 ` Tony Luck 2009-04-28 18:34 ` Matt Mackall 2009-04-28 18:34 ` Matt Mackall 2009-04-28 20:47 ` Tony Luck 2009-04-28 20:47 ` Tony Luck 2009-04-28 20:54 ` Andi Kleen 2009-04-28 20:54 ` Andi Kleen 2009-04-28 20:59 ` Matt Mackall 2009-04-28 20:59 ` Matt Mackall 2009-04-28 21:17 ` Andrew Morton 2009-04-28 21:17 ` Andrew Morton 2009-04-28 21:49 ` Matt Mackall 2009-04-28 21:49 ` Matt Mackall 2009-04-29 0:02 ` Robin Holt 2009-04-29 0:02 ` Robin Holt 2009-04-28 17:49 ` Matt Mackall 2009-04-28 17:49 ` Matt Mackall 2009-04-29 8:05 ` Wu Fengguang 2009-04-29 8:05 ` Wu Fengguang 2009-04-29 19:13 ` Matt Mackall 2009-04-29 19:13 ` Matt Mackall 2009-04-30 1:00 ` Wu Fengguang 2009-04-30 1:00 ` Wu Fengguang 2009-04-28 21:32 ` Andrew Morton 2009-04-28 21:32 ` Andrew Morton 2009-04-28 22:46 ` Matt Mackall 2009-04-28 22:46 ` Matt Mackall 2009-04-28 23:02 ` Andrew Morton 2009-04-28 23:02 ` Andrew Morton 2009-04-28 23:31 ` Matt Mackall 2009-04-28 23:31 ` Matt Mackall 2009-04-28 23:42 ` Andrew Morton 2009-04-28 23:42 ` Andrew Morton 2009-04-28 23:55 ` Matt Mackall 2009-04-28 23:55 ` Matt Mackall 2009-04-29 3:33 ` Wu Fengguang 2009-04-29 3:33 ` Wu Fengguang 2009-04-29 2:38 ` Wu Fengguang 2009-04-29 2:38 ` Wu Fengguang 2009-04-29 2:55 ` Andrew Morton 2009-04-29 2:55 ` Andrew Morton 2009-04-29 3:48 ` Wu Fengguang 2009-04-29 3:48 ` Wu Fengguang 2009-04-29 5:09 ` Wu Fengguang 2009-04-29 5:09 ` Wu Fengguang 2009-04-29 4:41 ` Nathan Lynch 2009-04-29 4:41 ` Nathan Lynch 2009-04-29 4:41 ` Nathan Lynch 2009-04-29 4:50 ` Andrew Morton 2009-04-29 4:50 ` Andrew Morton 2009-04-29 4:50 ` Andrew Morton
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