From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Date: Thu, 24 Feb 2011 18:46:37 +0000 Subject: Re: [PATCH V5 2/2] tracing, perf : add cpu hotplug trace events Message-Id: <1298573197.2428.457.camel@twins> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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.