Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752035AbaGJSD4 (ORCPT ); Thu, 10 Jul 2014 14:03:56 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.231]:7905 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751919AbaGJSDx (ORCPT ); Thu, 10 Jul 2014 14:03:53 -0400 Date: Thu, 10 Jul 2014 14:03:50 -0400 From: Steven Rostedt To: "Javi Merino" Cc: "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Punit Agrawal , "broonie@kernel.org" , Zhang Rui , Eduardo Valentin , Frederic Weisbecker , Ingo Molnar Subject: Re: [RFC PATCH v5 09/10] thermal: add trace events to the power allocator governor Message-ID: <20140710140350.5c75fee9@gandalf.local.home> In-Reply-To: <20140710162014.GB2622@e104805> References: <1405001928-12697-1-git-send-email-javi.merino@arm.com> <1405001928-12697-10-git-send-email-javi.merino@arm.com> <20140710114451.4bbf6785@gandalf.local.home> <20140710162014.GB2622@e104805> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.118:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 10 Jul 2014 17:20:14 +0100 "Javi Merino" wrote: > > > > How many CPUs are you saving load_cpu on? A trace event can't be bigger > > than a page. And the data is actually a little less than that with the > > required headers. > > The biggest system I've tested it on is an 8 cpu system (with > NR_CPUS==8). So yes, small and we haven't seen any issues. > > Are you saying that we are siphoning too much data through ftrace? He > find it really valuable to collect information during run and process > it afterwards but I can see how this may not be feasible for systems > with thousands of cpus. Only too much for a single event. Perhaps have the tracepoint post per CPU? Then you wouldn't need that array. -- Steve -- 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/