From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Javi Merino" Subject: Re: [RFC PATCH v5 09/10] thermal: add trace events to the power allocator governor Date: Fri, 11 Jul 2014 09:27:55 +0100 Message-ID: <20140711082755.GA2723@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> <20140710140350.5c75fee9@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20140710140350.5c75fee9@gandalf.local.home> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Steven Rostedt Cc: "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Punit Agrawal , "broonie@kernel.org" , Zhang Rui , Eduardo Valentin , Frederic Weisbecker , Ingo Molnar List-Id: linux-pm@vger.kernel.org On Thu, Jul 10, 2014 at 07:03:50PM +0100, Steven Rostedt wrote: > 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. Sounds good, I'll do that.