From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756036Ab1BXSqy (ORCPT ); Thu, 24 Feb 2011 13:46:54 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:40513 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753899Ab1BXSqw convert rfc822-to-8bit (ORCPT ); Thu, 24 Feb 2011 13:46:52 -0500 Subject: Re: [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events From: Peter Zijlstra To: Vincent Guittot Cc: linux-kernel@vger.kernel.org, linux-hotplug@vger.kernel.org, Frederic Weisbecker , Steven Rostedt , amit.kucheria@linaro.org, Rusty Russell , Ingo Molnar , Thomas Gleixner In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 24 Feb 2011 19:46:37 +0100 Message-ID: <1298573197.2428.457.camel@twins> 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 On Thu, 2011-02-24 at 18:33 +0100, Vincent Guittot wrote: > The goal is to measure the latency of each part (kernel, architecture) > and also to trace the cpu hotplug activity with other power events. I > have tested these traces events on an arm platform. > this patch adds new events for cpu hotplug tracing > * plug/unplug sequence > * core and architecture latency measurements Aside of the points tglx made, I do have to ask _WHY_!? Anybody who is interested in the latency of cpu hotplug is deluding himself, also cpu hotplug is _NOT_ a power management feature, so the rest of your justification just disappeared as well.