From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p0P8YOSr221541 for ; Tue, 25 Jan 2011 02:34:25 -0600 Received: from ipmail04.adl6.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 7F5188AA020 for ; Tue, 25 Jan 2011 00:36:46 -0800 (PST) Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id 9QHD63HP1CiejvB1 for ; Tue, 25 Jan 2011 00:36:46 -0800 (PST) Date: Tue, 25 Jan 2011 19:36:43 +1100 From: Dave Chinner Subject: Re: Optimize RAID0 for max IOPS? Message-ID: <20110125083643.GE28803@dastard> References: <20110118210112.D13A236C@gemini.denx.de> <4D361F26.3060507@stud.tu-ilmenau.de> <20110119192104.1FA92D30267@gemini.denx.de> <20110124215713.82D75B187@gemini.denx.de> <20110124230314.GA11040@dastard> <20110125083900.4dd65bf2@galadriel2.home> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20110125083900.4dd65bf2@galadriel2.home> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Emmanuel Florac Cc: linux-raid@vger.kernel.org, xfs@oss.sgi.com, Wolfgang Denk , Justin Piszcz [ As a small note - if you are going to comment on the results table from a previous message, please don't cut it from your response. Context is important. I pasted the relevant part back in so i can refer back to it in my response. ] On Tue, Jan 25, 2011 at 08:39:00AM +0100, Emmanuel Florac wrote: > Le Tue, 25 Jan 2011 10:03:14 +1100 vous =E9criviez: > > > Version 1.96 ------Sequential Create------ --------Random Crea= te-------- > > > A1 -Create-- --Read--- -Delete-- -Create-- --Read---= -Delete-- > > > files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP= /sec %CP > > > 16 104 0 +++++ +++ 115 0 89 0 +++++ +++= 111 0 > > = > > Only 16 files? > = > IIRC this is 16 thousands of files. Though this is not enough, I > generally use 80 to 160 for tests. Yes, you're right, the bonnie++ man page states that it is in units of 1024 files. Be nice if there was a "k" to signify that so people who aren't intimately familiar with it's output format can see exactly what was tested.... As it is, a create rate of 104 files/s (note the consistency of units between 2 adjacent numbers!) indicates something else is screwed, because my local test VM on RAID0 gets numbers like this: Version 1.96 ------Sequential Create------ --------Random Create----= ---- test-4 -Create-- --Read--- -Delete-- -Create-- --Read--- -Dele= te-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec= %CP 16 25507 90 +++++ +++ 30472 97 25281 93 +++++ +++ 29077= 97 Latency 23864us 204us 21092us 18855us 82us 121= us IOWs, create rates of 25k/s and unlink of 30k/s and it is clearly CPU bound. Therein lies the difference: the original numbers have 0% CPU usage, which indicates that the test is blocking. Something is causing the reported test system to be blocked almost all the time. /me looks closer. Oh, despite $subject being "RAID0" the filesystems being tested are on RAID5 and RAID6 with very small chunk sizes on slow SATA drives. This is smelling like a case of barrier IOs on software raid on cheap storage.... Cheers, Dave. -- = Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs