From: Ted Ts'o Subject: Re: High CPU Utilization When Copying to Ext4 Date: Wed, 29 Jun 2011 22:33:06 -0400 Message-ID: <20110630023306.GY2729@thunk.org> References: <341DAA96EE3A8444B6E4657BE8A846EA4B3DA126FE@NDJSSCC06.ndc.nasa.gov> <20110627030539.GF3064@thunk.org> <341DAA96EE3A8444B6E4657BE8A846EA4B3DA12708@NDJSSCC06.ndc.nasa.gov> <341DAA96EE3A8444B6E4657BE8A846EA4B3DA1270A@NDJSSCC06.ndc.nasa.gov> <50F503A1-6A16-41C4-9C27-0662063C7817@mit.edu> <4E0BBCE9.9020600@nasa.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-ext4@vger.kernel.org" To: Sean McCauliff Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:55074 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757529Ab1F3CdJ (ORCPT ); Wed, 29 Jun 2011 22:33:09 -0400 Content-Disposition: inline In-Reply-To: <4E0BBCE9.9020600@nasa.gov> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jun 29, 2011 at 05:01:45PM -0700, Sean McCauliff wrote: > Sorry, I didn't mean to bother you. I did try and email ext3-users > so as to not take up any developer time with my question. Yeah, but it's not likely anyone on that list would be able to help you. Both ext3 and ext4 isn't expected to take a huge amount of CPU under normal conditions when doing this type of copying where you will be likely disk bound. Well, you're not using fallocate() (at least you haven't disclosed it to date), and writing into fallocated space is the only thing that would be using a workqueue at all (which is what the kworker threads are using). So I very much doubt it has anything to do with ext4. The fiber channel drivers do use workqueues a fair amount, so yes, it would be useful to know that you are using a fiber channel SAN. At this point I'd suggest that you use oprofile or perf to see where the CPU is being consumed. Perf is probably better since it will allow you to see the call chains. - Ted