From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754751Ab1ALPK3 (ORCPT ); Wed, 12 Jan 2011 10:10:29 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:62424 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753744Ab1ALPK1 (ORCPT ); Wed, 12 Jan 2011 10:10:27 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=IghxxZv1FuDrXajJhvMwyfspv6/xx9vdFNiaGrP/PfoUACLwkJZc1Lv3qYM4BbFPmT 4I0d/qwshWKAuB1b15oKdrWhTnIqL+ZJFwgbaZKKqxSFhzCSdKETEiarK39ClM9dtsBd mdbyPuuIEtZSaKaqEpq/3YwvnNxOubbIjhScQ= Date: Wed, 12 Jan 2011 16:10:23 +0100 From: Frederic Weisbecker To: Peter Zijlstra Cc: Kirill Smelkov , linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Ingo Molnar , Mike Galbraith , Paul Mackerras , Stephane Eranian , Tom Zanussi Subject: Re: Q: perf log mode? Message-ID: <20110112151020.GB1755@nowhere> References: <20110112140613.GA11698@tugrik.mns.mnsspb.ru> <1294841288.19601.49.camel@laptop> <20110112144240.GA1755@nowhere> <1294844021.19601.51.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1294844021.19601.51.camel@laptop> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 12, 2011 at 03:53:41PM +0100, Peter Zijlstra wrote: > On Wed, 2011-01-12 at 15:42 +0100, Frederic Weisbecker wrote: > > On Wed, Jan 12, 2011 at 03:08:08PM +0100, Peter Zijlstra wrote: > > > On Wed, 2011-01-12 at 17:06 +0300, Kirill Smelkov wrote: > > > > I'm trying to use perf together with e.g. kprobes as a tool to show what > > > > is happening with my system in "live-log" mode. The problem is, for > > > > seldom events, actual info output is largely delayed because perf reads > > > > sample data in whole pages. Could something be done with it or am I'm > > > > missing something? Here is detailed description: > > > > > > perf_event_attr = { > > > .watermark = 0, > > > .wakeup_events = 1, > > > }; > > > > > > Which is perhaps something we want as a default when perf record -c 1 > > and the output is the pipe mode. > > No, definitely not, esp for -c1 you want large buffers because the event > can come at very high freq. Right this should not be a default actually if we have high freq events we don't want wake up at each of them. > Nor does pipe mode have anything to do with it, the whole script set-up > plain stinks Oh? What's wrong with the scripts infrastructure? > and should not be using pipe mode, pipe mode should only be > used to pipe data over the network and other remote profiling like > things. But the scripts are just an endpoint over many other possibilities, regardless of what is in the middle: perf.data or pipe streaming. Where is a limitation on using scripts here?