Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755481Ab0KVMXn (ORCPT ); Mon, 22 Nov 2010 07:23:43 -0500 Received: from ist.d-labs.de ([213.239.218.44]:38472 "EHLO mx01.d-labs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754525Ab0KVMXl (ORCPT ); Mon, 22 Nov 2010 07:23:41 -0500 Date: Mon, 22 Nov 2010 13:23:06 +0100 From: Florian Mickler To: Peter Zijlstra Cc: John Stultz , lkml , Mike Chan , Ingo Molnar Subject: Re: [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies Message-ID: <20101122132306.245e0bcb@schatten.dmk.lab> In-Reply-To: <1290422639.2110.3.camel@laptop> 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> <1290422639.2110.3.camel@laptop> X-Mailer: Claws Mail 3.7.6cvs31 (GTK+ 2.20.1; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2130 Lines: 57 On Mon, 22 Nov 2010 11:43:59 +0100 Peter Zijlstra wrote: > 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. > > :) what I wanted to get at, was that they probably need these stats aggregated somewhere neat and tidy and can not compute them on the fly recording massive amounts of data... I wonder why they didn't put this in the idle-driver. I don't know. Regards, Flo -- 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/