Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751967Ab3IQHQs (ORCPT ); Tue, 17 Sep 2013 03:16:48 -0400 Received: from mail-bk0-f52.google.com ([209.85.214.52]:46201 "EHLO mail-bk0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751434Ab3IQHQp (ORCPT ); Tue, 17 Sep 2013 03:16:45 -0400 Date: Tue, 17 Sep 2013 09:16:41 +0200 From: Ingo Molnar To: Namhyung Kim Cc: Frederic Weisbecker , LKML , Jiri Olsa , David Ahern , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Stephane Eranian , Linus Torvalds Subject: Re: [PATCH 0/4] perf tools: New comm infrastructure Message-ID: <20130917071641.GD20661@gmail.com> References: <1379017783-27032-1-git-send-email-fweisbec@gmail.com> <20130912203658.GA3216@gmail.com> <20130913124354.GB4844@somewhere> <20130914061148.GF364@gmail.com> <87li2wq9gx.fsf@sejong.aot.lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87li2wq9gx.fsf@sejong.aot.lge.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3410 Lines: 87 * Namhyung Kim wrote: > Hi Ingo, > > On Sat, 14 Sep 2013 08:11:49 +0200, Ingo Molnar wrote: > > * Frederic Weisbecker wrote: > >> My patches and Namhyung's should improve the comm situation a lot but we > >> can't do much miracle. The only way would be perhaps to be able to limit > >> the deepness of the callchain branches. > >> > >> Now may be we can find other big contention point in perf. It's possible > >> we also have some endless loop somewhere. > > > > Well, it was the 100,000+ step linear list walk that was causing 90% of > > the slowness here. Namhyung's patch should dramatically improve that. I > > guess time for someone to post a combined tree so that it can be tested > > all together? > > I pushed combined tree to 'perf/callchain-v2' branch in my tree > > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > > Please note that I also pushed other versions (v[1-3]). The v1 is my > previous rbtree conversion patch, v2 adds Frederic's new comm > infrastructure series on top and v3 adds my revised patch to refer > current comm [1] on top of v2. > > I did my own test again among them. Test data is 400MB perf.data file > created by parallel kernel build. > > $ ls -lh perf.data.big > -rw-------. 1 namhyung namhyung 400M Sep 9 10:21 perf.data.big > > For more precise result, I changed cpufreq governor to 'performance' Btw., > > # echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor > > and run perf report on the cpu. > > $ taskset -c 3 time -p perf --no-pager report --stdio -i perf.data.big > /dev/null Btw., for such things you could use 'perf stat --null --sync --repeat 3', which will not use the PMU or even perf events, it only uses precise timers to measure execution time: $ taskset -c 3 perf stat --null --sync --repeat 3 -p perf --no-pager report --stdio -i perf.data.big > /dev/null > I ran it multiple times for each case and the results did not vary much. (perf stat --repeat will print a nice stddev as well.) > baseline v1 v2 v3 > ---------------------------------------------------------- > real 380.17 12.63 10.02 9.03 > user 378.86 11.95 9.66 8.69 > sys 0.70 0.65 0.33 0.34 (Alas perf stat --null does not print a system/user time split. Might be nice to implement that.) The numbers look pretty nice, a 40x speedup. Especially with the progress bar displayed this should be within a human-tolerable runtime. Still it would be nice to look at some stats: number of records, number of call chain entries, average call chain depth, tree size, max tree depth, etc. - so that we get a processing cost estimation of how much we spend on a single call chain entry, on average. If any of those values is suspiciously high then maybe we could cull the callchain depth by default, people rarely look beyond a couple of entries: but this gets tricky when people sort in the reverse direction though - in that case the deepest entries are just as valuable as well to the end result. Thanks, Ingo -- 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/