From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751923Ab3KSAey (ORCPT ); Mon, 18 Nov 2013 19:34:54 -0500 Received: from mail-pb0-f43.google.com ([209.85.160.43]:65066 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751850Ab3KSAew (ORCPT ); Mon, 18 Nov 2013 19:34:52 -0500 Message-ID: <528AB229.6030603@gmail.com> Date: Mon, 18 Nov 2013 17:34:49 -0700 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Namhyung Kim , Ingo Molnar CC: Peter Zijlstra , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, jolsa@redhat.com, Frederic Weisbecker , Mike Galbraith , Stephane Eranian Subject: Re: [PATCH 4/5] perf record: mmap output file - v5 References: <1384267617-3446-1-git-send-email-dsahern@gmail.com> <1384267617-3446-5-git-send-email-dsahern@gmail.com> <20131112145707.GV5056@laptop.programming.kicks-ass.net> <20131112150751.GA19321@ghostprotocols.net> <20131112151944.GX5056@laptop.programming.kicks-ass.net> <52824AE3.4050207@gmail.com> <20131112211121.GC25913@gmail.com> <20131113113439.GI21461@twins.programming.kicks-ass.net> <52864ED1.1080607@gmail.com> <20131118090117.GE3866@twins.programming.kicks-ass.net> <20131118094036.GA26251@gmail.com> <877gc5utkf.fsf@sejong.aot.lge.com> In-Reply-To: <877gc5utkf.fsf@sejong.aot.lge.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/18/13, 5:24 PM, Namhyung Kim wrote: >>>> What now? Can we add the mmap path as an option? >>> >>> I'd say an option is always a possibility, but someone please try >>> what happens if you use stupid large events (dwarf stack copies) on >>> PERF_COUNT_SW_PAGE_FAULTS (.period=1) while recording with mmap(). >>> >>> The other option is to simply disallow PERF_SAMPLE_STACK_USER for >>> that event. >>> >>> Personally I think 8k copies for every event are way stupid anyway, >>> that's a metric ton of data at a huge cost. >> >> Well, with 1 khz sampling of a single threaded workload it's 8MB per >> second - that's 80 MB for 10 seconds profiling - not the end of the >> world. > > We now use 4 khz sampling frequency by default, just FYI. :) I think Peter is asking about: perf record -e faults -c 1 --call-graph dwarf,8192 -a -- sleep 1 And as expected it is a massive feedback spiraling out of control. David