From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id F1F3D7FF2 for ; Sun, 17 Feb 2013 15:25:56 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id 9ED61AC001 for ; Sun, 17 Feb 2013 13:25:53 -0800 (PST) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id GbutpMXHHIBWPjfp for ; Sun, 17 Feb 2013 13:25:52 -0800 (PST) Date: Mon, 18 Feb 2013 08:25:36 +1100 From: Dave Chinner Subject: Re: High %user CPU in XFS Message-ID: <20130217212536.GY26694@dastard> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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 Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Subranshu Patel Cc: xfs@oss.sgi.com On Sun, Feb 17, 2013 at 09:20:46PM +0530, Subranshu Patel wrote: > I created 2 filesystem on my system (RHEL 6.3, kernel 2.6.32) - XFS > and EXT4 and mounted them. > > On both the filesystem I executed a program which performed the following: > - Create large number of directories > - Removing all the directories > > During the execution of the program, I monitored the %user and %system > CPU usage (using sar command) > > For EXT4 the %user was 1% and %system was 21% > For XFS the %user was 20% and %system was 52% > > But I am not able to understand %user consumption, since %user reports > the CPU usage of the user level (application), shouldn't it be the > same for both EXT4 and XFS? Perf is your friend. > What are the factors that decide the %user component keeping in mind > that only the filesystem is different? Page faults, CPU cache misses. XFS has a significantly large icache and dcache footprint than ext4, so those are the likely causes. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs