From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756419Ab0EaIBE (ORCPT ); Mon, 31 May 2010 04:01:04 -0400 Received: from fallback.mail.elte.hu ([157.181.151.13]:52404 "EHLO fallback.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756308Ab0EaIA6 (ORCPT ); Mon, 31 May 2010 04:00:58 -0400 Date: Mon, 31 May 2010 10:00:49 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: Frederic Weisbecker , LKML , Steven Rostedt Subject: Re: [PATCH] tracing: Add task activate/deactivate tracepoints Message-ID: <20100531080049.GA435@elte.hu> References: <1275056762-13130-1-git-send-regression-fweisbec@gmail.com> <1275059710.27810.9624.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1275059710.27810.9624.camel@twins> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 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 * Peter Zijlstra wrote: > On Fri, 2010-05-28 at 16:26 +0200, Frederic Weisbecker wrote: > > We have various tracepoints that tell us when a task is going to > > be enqueued in a runqueue: fork, wakeup, migrate. > > > > But they don't always provide us the level of information necessary > > to know what is actually in which runqueue, precisely because the > > migrate event is only fired if the task is queued on another > > cpu than its previous one. So we don't always know where a waking up > > task goes. > > > > And moreover we don't have events that tells a task goes to sleep, > > and even that wouldn't cover every cases when a task is dequeued. > > > > So bring these two new tracepoints to get informations about the > > load of each runqueues. > > NAK, aside from a few corner cases wakeup and sleep are the important > points. > > The activate and deactivate functions are implementation details. Frederic, can you show us a concrete example of where we dont know what is going on due to inadequate instrumentation? Can we fix that be extending the existing tracepoints? Ingo