From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752330AbbFXJCv (ORCPT ); Wed, 24 Jun 2015 05:02:51 -0400 Received: from casper.infradead.org ([85.118.1.10]:35909 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752021AbbFXJBv (ORCPT ); Wed, 24 Jun 2015 05:01:51 -0400 Date: Wed, 24 Jun 2015 11:01:42 +0200 From: Peter Zijlstra To: Ingo Molnar Cc: Daniel Wagner , 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: <20150624090142.GJ3644@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> <20150623143411.GA25159@twins.programming.kicks-ass.net> <558973A7.6010407@bmw-carit.de> <20150623175012.GD3644@twins.programming.kicks-ass.net> <20150623193624.GH18673@twins.programming.kicks-ass.net> <20150624084648.GB27873@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150624084648.GB27873@gmail.com> 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 Wed, Jun 24, 2015 at 10:46:48AM +0200, Ingo Molnar wrote: > > > > flock02 > > > > mean variance sigma max min > > > > tip-1 11.8994 0.5874 0.7664 13.2022 8.6324 > > > > tip-2 11.7394 0.5252 0.7247 13.2540 9.7513 > > > > tip-3 11.8155 0.5288 0.7272 13.2700 9.9480 > > > > tip+percpu-rswem-1 15.3601 0.8981 0.9477 16.8116 12.6910 > > > > tip+percpu-rswem-2 15.2558 0.8442 0.9188 17.0199 12.9586 > > > > tip+percpu-rswem-3 15.5297 0.6386 0.7991 17.4392 12.7992 > [ Such high variance is often caused by (dynamically) unstable load balancing and > the workload never finding a good equilibrium. Any observable locking overhead > is usually just a second order concern or a symptom. Assuming the workload > context switches heavily. ] flock02 is a relatively stable benchmark -- unlike some of the others where the variance is orders of magnitude higher than the avg. But yes, I'll go poke at it more. I just need to hunt down unrelated fail before continuing with this.