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 oAU4RaNw025970 for ; Mon, 29 Nov 2010 22:27:37 -0600 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 5A75E13FCABB for ; Mon, 29 Nov 2010 20:29:16 -0800 (PST) Received: from mail.internode.on.net (bld-mail17.adl2.internode.on.net [150.101.137.102]) by cuda.sgi.com with ESMTP id hMIetAXRHDsdZwIg for ; Mon, 29 Nov 2010 20:29:16 -0800 (PST) Date: Tue, 30 Nov 2010 15:29:13 +1100 From: Dave Chinner Subject: Re: XFS: performance Message-ID: <20101130042913.GB3556@dastard> References: <20101129001112.GA28672@dastard> <20101129015937.GB28672@dastard> <4CF33D0F.6080404@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4CF33D0F.6080404@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Stan Hoeppner Cc: xfs@oss.sgi.com On Sun, Nov 28, 2010 at 11:41:35PM -0600, Stan Hoeppner wrote: > Yclept Nemo put forth on 11/28/2010 9:57 PM: > > You mention an eight-core machine (8c?). Since I operate a dual-core > > system, would it make sense to increase my AG count slightly, to five > > or six? > > Dave didn't mention the disk configuration of his "workstation". I'm > guessing he's got a local RAID setup with 8-16 drives. 2 SSDs in RAID0. > AG count has a > direct relationship to the storage hardware, not the number of CPUs > (cores) in the system. Actually, I used 16 AGs because it's twice the number of CPU cores and I want to make sure that CPU parallel workloads (e.g. make -j 8) don't serialise on AG locks during allocation. IOWs, I laid it out that way precisely because of the number of CPUs in the system... And to point out the not-so-obvious, this is the _default layout_ that mkfs.xfs in the debian squeeze installer came up with. IOWs, mkfs.xfs did exactly what I wanted without me having to tweak _anything_. > If you have a 24 core system (2x Magny Cours) > and a single disk, creating an FS with 24 AGs will give you nothing, and > may actually impede performance due to all the extra head seeking across > those 24 AGs. In that case, you are right. Single spindle SRDs go backwards in performance pretty quickly once you go over 4 AGs... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs