From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924AbbAICsJ (ORCPT ); Thu, 8 Jan 2015 21:48:09 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:39646 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753065AbbAICsF (ORCPT ); Thu, 8 Jan 2015 21:48:05 -0500 Message-ID: <1420771673.12346.16.camel@stgolabs.net> Subject: Re: [LKP] [mm] c8c06efa8b5: -7.6% unixbench.score From: Davidlohr Bueso To: Huang Ying Cc: LKML , LKP ML Date: Thu, 08 Jan 2015 18:47:53 -0800 In-Reply-To: <1420684064.6201.86.camel@linux.intel.com> References: <1420684064.6201.86.camel@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-01-08 at 10:27 +0800, Huang Ying wrote: > FYI, we noticed the below changes on > > commit c8c06efa8b552608493b7066c234cfa82c47fcea ("mm: convert i_mmap_mutex to rwsem") > > > testbox/testcase/testparams: lituya/unixbench/performance-execl > > 83cde9e8ba95d180 c8c06efa8b552608493b7066c2 > ---------------- -------------------------- > %stddev %change %stddev > \ | \ > 721721 ± 1% +303.6% 2913110 ± 3% unixbench.time.voluntary_context_switches > 11767 ± 0% -7.6% 10867 ± 1% unixbench.score I simply cannot reproduce this, not even on a large box. mutex (83cde9e8ba95d180): run1: Execl Throughput 3974.3 lps (30.0 s, 2 samples) Voluntary context switches: 377039 run2: Execl Throughput 4115.5 lps (30.0 s, 2 samples) Voluntary context switches: 391260 run3: Execl Throughput 4000.2 lps (30.0 s, 2 samples) Voluntary context switches: 378674 rwsem (c8c06efa8b552608493b7066c2): run1: Execl Throughput 4166.0 lps (30.0 s, 2 samples) Voluntary context switches: 385740 run2: Execl Throughput 4115.5 lps (30.0 s, 2 samples) Voluntary context switches: 391260 run3: Execl Throughput 4110.5 lps (29.9 s, 2 samples) Voluntary context switches: 387053 Since throughput is in the ballpark, so is the benchmark score (in fact the rwsem score is slightly better). Is this a one time thing or can you observe it again? Any special things you guys are doing when running the benchmark? Here are some things I've done: cpu gov set to performance, Unixbench taken from (http://byte-unixbench.googlecode.com/files/UnixBench5.1.3.tgz ), used default compiler options from unixbench Makefile (that is using the solaris 2 option). This pretty much matches the environment info you've provided. We've done this lock type comparison exercise plenty of times in the past, and I'm a bit surprised to see your numbers. Thanks, Davidlohr