From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933427AbbFWOe0 (ORCPT ); Tue, 23 Jun 2015 10:34:26 -0400 Received: from casper.infradead.org ([85.118.1.10]:58199 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932514AbbFWOeV (ORCPT ); Tue, 23 Jun 2015 10:34:21 -0400 Date: Tue, 23 Jun 2015 16:34:11 +0200 From: Peter Zijlstra To: Daniel Wagner Cc: oleg@redhat.com, paulmck@linux.vnet.ibm.com, tj@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org, der.herr@hofr.at, dave@stgolabs.net, riel@redhat.com, viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org, jlayton@poochiereds.net Subject: Re: [RFC][PATCH 00/13] percpu rwsem -v2 Message-ID: <20150623143411.GA25159@twins.programming.kicks-ass.net> References: <20150622121623.291363374@infradead.org> <55884FC2.6030607@bmw-carit.de> <20150622190553.GZ3644@twins.programming.kicks-ass.net> <5589285C.2010100@bmw-carit.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5589285C.2010100@bmw-carit.de> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 23, 2015 at 11:35:24AM +0200, Daniel Wagner wrote: > flock01 > mean variance sigma max min > 4.1.0 11.7075 816.3341 28.5716 125.6552 0.0021 > 4.1.0+percpu-rwsem 11.4614 760.1345 27.5705 132.5030 0.0026 > tip 6.8390 329.3037 18.1467 81.0373 0.0021 > tip+percpu-rwsem 10.0870 546.7435 23.3825 106.2396 0.0026 > posix01 > mean variance sigma max min > 4.1.0 121.9020 27882.5260 166.9806 603.5509 0.0063 > 4.1.0+percpu-rwsem 185.3981 38474.3836 196.1489 580.6532 0.0073 > tip 129.2736 23752.7122 154.1191 474.0604 0.0063 > tip+percpu-rwsem 142.6474 24732.1571 157.2646 468.7478 0.0072 Both these tests are incredibly unstable for me (as well as for you it appears). Variance is through the roof on them. I get runtimes like: root@ivb-ex:/usr/local/src/lockperf# ./flock01 -n 240 -l 32 /tmp/a 0.266157011 root@ivb-ex:/usr/local/src/lockperf# ./flock01 -n 240 -l 32 /tmp/a 139.303399960 That's not really inspiring, if I use bigger loop counts it more or less settles, but then the EX is unusable because it ends up running 3000 seconds per test. In any case, on a smaller box (ivb-ep) I got the below results: posix01 mean variance sigma max min data-4.1.0-02756-ge3d06bd 250.7032 40.4864 6.3629 263.7736 238.5192 data-4.1.0-02756-ge3d06bd-dirty 252.6847 35.8953 5.9913 270.1679 233.0215 Which looks better, but the difference is still well within the variance and thus not significant. Lemme continue playing with this for a bit more.