Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753874Ab0KVKnl (ORCPT ); Mon, 22 Nov 2010 05:43:41 -0500 Received: from casper.infradead.org ([85.118.1.10]:60142 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753116Ab0KVKnk convert rfc822-to-8bit (ORCPT ); Mon, 22 Nov 2010 05:43:40 -0500 Subject: Re: [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies From: Peter Zijlstra To: Florian Mickler Cc: John Stultz , lkml , Mike Chan , Ingo Molnar In-Reply-To: <20101122065129.072bba06@schatten.dmk.lab> References: <1290218934-8544-1-git-send-email-john.stultz@linaro.org> <1290218934-8544-4-git-send-email-john.stultz@linaro.org> <1290250104.2118.4.camel@laptop> <20101122065129.072bba06@schatten.dmk.lab> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 22 Nov 2010 11:43:59 +0100 Message-ID: <1290422639.2110.3.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1712 Lines: 41 On Mon, 2010-11-22 at 06:51 +0100, Florian Mickler wrote: > On Sat, 20 Nov 2010 11:48:24 +0100 > Peter Zijlstra wrote: > > > On Fri, 2010-11-19 at 18:08 -0800, John Stultz wrote: > > > From: Mike Chan > > > > > > Introduce new platform callback hooks for cpuacct for tracking CPU frequencies > > > > > > Not all platforms / architectures have a set CPU_FREQ_TABLE defined > > > for CPU transition speeds. In order to track time spent in at various > > > CPU frequencies, we enable platform callbacks from cpuacct for this accounting. > > > > > > Architectures that support overclock boosting, or don't have pre-defined > > > frequency tables can implement their own bucketing system that makes sense > > > given their cpufreq scaling abilities. > > > > > > New file: > > > cpuacct.cpufreq reports the CPU time (in nanoseconds) spent at each CPU > > > frequency. > > > > I utterly detest all such accounting crap.. it adds ABI constraints it > > add runtime overhead. etc.. > > > > Can't you get the same information by using the various perf bits? If > > you trace the cpufreq changes you can compute the time spend in each > > power state, if you additionally trace the sched_switch you can compute > > it for each task. > > > > > This is probably used for "on-site" debugging of production systems. Dude, its from the _android_ tree... its cpufreq crud.. it must be some crack induced power management scheme. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/