From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933085AbXCUHlA (ORCPT ); Wed, 21 Mar 2007 03:41:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933059AbXCUHlA (ORCPT ); Wed, 21 Mar 2007 03:41:00 -0400 Received: from brick.kernel.dk ([62.242.22.158]:27903 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933191AbXCUHk7 (ORCPT ); Wed, 21 Mar 2007 03:40:59 -0400 Date: Wed, 21 Mar 2007 08:40:14 +0100 From: Jens Axboe To: Davide Libenzi Cc: Linux Kernel Mailing List , Ingo Molnar , Linus Torvalds Subject: Re: AIO, FIO and Threads ... Message-ID: <20070321074014.GD14389@kernel.dk> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 20 2007, Davide Libenzi wrote: > > I was looking at Jens FIO stuff, and I decided to cook a quick patch for > FIO to support GUASI (Generic Userspace Asyncronous Syscall Interface): > > http://www.xmailserver.org/guasi-lib.html > > I then ran a few tests on my Dual Opteron 252 with SATA drives (sata_nv) > and 8GB of RAM. > Mind that I'm not FIO expert, like at all, but I got some interesting > results when comparing GUASI with libaio at 8/1000/10000 depths. > If I read those result correctly (Jens may help), GUASI output is more > then double the libaio one. > Lots of context switches, yes. But the throughput looks like 2+ times. > Can someone try to repeat the measures and/or spot the error? > Or tell me which other tests to run? > This is kinda a suprise for me ... I don't know guasi at all, but libaio requires O_DIRECT to be async. I'm sure you know this, but you may not know that fio default to buffered IO so you have to tell it to use O_DIRECT :-) So try adding a --direct=1 (or --buffered=0, same thing) as an extra option when comparing depths > 1. I'll add your guasi engine, but disable it. Unfortunately fio still doesn't have a nifty configure setup, so these things are still manual... -- Jens Axboe