From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751763Ab2EMEk5 (ORCPT ); Sun, 13 May 2012 00:40:57 -0400 Received: from li9-11.members.linode.com ([67.18.176.11]:45019 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750831Ab2EMEkz (ORCPT ); Sun, 13 May 2012 00:40:55 -0400 Date: Sun, 13 May 2012 00:40:52 -0400 From: "Ted Ts'o" To: =?iso-8859-1?Q?Bj=F6rn?= Christoph Cc: linux-kernel@vger.kernel.org Subject: Re: BUG: jbd2 slowing down file copies even though no journaling file system is used Message-ID: <20120513044052.GC31866@thunk.org> Mail-Followup-To: Ted Ts'o , =?iso-8859-1?Q?Bj=F6rn?= Christoph , linux-kernel@vger.kernel.org References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on test.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 13, 2012 at 01:21:00AM +0200, Björn Christoph wrote: > > IOTOP shows this in some cases, mostly jbd2 is not there: >   PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND >   416 be/3 root        0.00 B/s   97.65 M/s  0.00 % 13.74 % [jbd2/dm-1-8] Well, the file system in that has the huge write bandwidth is whichever device is associated with device mapper device dm-1 (i.e., with a device mapper minor number of 1). What does "ls -l /dev/mapper" show you? Whatever file system is associated with it is clearly generating a lot of journal activity. Something that may help in determining what process is generating all of this journal activity (which is likely the result of something calling fsync a lot) is to try this: echo 1 > /sys/kernel/debug/tracing/events/ext4/ext4_sync_file_enter/enable ... then wait for a minute or so, and then capture the output of: cat /sys/kernel/debug/tracing/trace See if that shows up anything useful. Regards, - Ted