From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760254AbYDQSwY (ORCPT ); Thu, 17 Apr 2008 14:52:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752237AbYDQSwP (ORCPT ); Thu, 17 Apr 2008 14:52:15 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:35242 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751603AbYDQSwO (ORCPT ); Thu, 17 Apr 2008 14:52:14 -0400 Date: Thu, 17 Apr 2008 20:51:58 +0200 From: Ingo Molnar To: Andrew Morton Cc: Christoph Hellwig , Pekka Enberg , linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven Subject: Re: [v2.6.26] what's brewing in x86.git for v2.6.26 Message-ID: <20080417185158.GA26603@elte.hu> References: <20080416202338.GA6007@elte.hu> <20080417002552.5742ad65.akpm@linux-foundation.org> <84144f020804170045s24cbb802u3358ec6b5d391a10@mail.gmail.com> <20080417012051.ed56f4ab.akpm@linux-foundation.org> <84144f020804170134k4c98f022xc247442592fb1a44@mail.gmail.com> <20080417014217.ab0453a9.akpm@linux-foundation.org> <20080417114900.GA17033@infradead.org> <20080417110135.08b076ac.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080417110135.08b076ac.akpm@linux-foundation.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton wrote: > afaik the sysprof-vs-oprofile issue still hasn't been settled. Maybe > it's no longer a relevant question with the new code - I just don't > know. Everything went all quiet and then this stuff happened. i dont think there's any big issue here. Sysprof is a time and stack system-wide tracer/profiler, oprofile profiles CPU events - deep stacktracing is an afterthought there. And how do you set up oprofile to do precise time events? with sysprof you can do: cd /sys/kernel/debug/tracing echo sysprof > current_tracer cat trace_pipe and you'll see the trace events go by, live. The user-space bits of sysprof have been ported over to ftrace/sysprof already and it's a really nice tool that shows a deep stack-trace based hierarchical "vertical" profile instead of the usual finegrained profile. It certainly helps that the author of the tracer plugin (Soeren Sandmann) is the author of the userspace app too - so there's a rather well-working feedback loop here ;-) With oprofile all these things are rather indirect, the API is more complex, it forces per-CPU buffers, etc. etc. I think for instrumentation the driving force must be usability, and sysprof/ftrace is hands down more usable - to me at least. Ingo