From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754175AbZIKH6b (ORCPT ); Fri, 11 Sep 2009 03:58:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754138AbZIKH6a (ORCPT ); Fri, 11 Sep 2009 03:58:30 -0400 Received: from brick.kernel.dk ([93.163.65.50]:36539 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753945AbZIKH6a (ORCPT ); Fri, 11 Sep 2009 03:58:30 -0400 Date: Fri, 11 Sep 2009 09:58:32 +0200 From: Jens Axboe To: Ingo Molnar Cc: Frans Pop , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [long] Another BFS versus CFS shakedown Message-ID: <20090911075832.GG18599@kernel.dk> References: <200909090142.41738.elendil@planet.nl> <20090911062032.GB27833@elte.hu> <200909110904.50487.elendil@planet.nl> <20090911071710.GB18599@kernel.dk> <20090911075331.GA14489@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090911075331.GA14489@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 11 2009, Ingo Molnar wrote: > > * Jens Axboe wrote: > > > On Fri, Sep 11 2009, Frans Pop wrote: > > > On Friday 11 September 2009, Ingo Molnar wrote: > > > > Note, the one you used was a still buggy version of latt.c producing > > > > bogus latency numbers - you will need the fix to it attached below. > > > > > > Yes, I'm aware of that and have already copied Jens' latest version. > > > > BTW, I put it in a git repo, it quickly gets really confusing with so > > many version going around. So that can be accessed here: > > > > git://git.kernel.dk/latt.git > > > > and as with my other repos, snapshots are automatically generated every > > hour when new commits have been made. To get the very latest latt and > > not have to use git, download: > > > > http://brick.kernel.dk/snaps/latt-git-latest.tar.gz > > Btw., your earlier latt reports should be discarded as invalid due > to that bug. Yes > With the fixed latt.c version the mainline latencies (both > worst-case and average) were reported to be better after the poll() > bug got fixed, so in that area, for this kind of measurement, > mainline seems to be working well. > > [ What happened is that the poll() bug was creating false latencies > in the mainline scheduler tests. (BFS avoided measuring that bug > incidentally, by its agressive balancer moved the wakee tasks away > from the buggy busy-looping poll() looping parent task. Two > instances of latt.c would possibly have shown similar latencies.) ] > > I see you added new 'work generator' changes to latt.c now, will > check/validate that version of latt.c too. I did, it's a simple 'generate random data and compress it' work piece for each client. You can control the amount of work with -x, which sets the kb of data it'll work on. Stats are generated both for wakeup latency, and work processing latency. -- Jens Axboe