From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: Query about DIO/AIO WRITE throttling and ext4 serialization Date: Fri, 3 Jun 2011 09:46:46 +1000 Message-ID: <20110602234646.GU561@dastard> References: <20110601215049.GC17449@redhat.com> <20110602012209.GQ561@dastard> <20110602141716.GD18712@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Vivek Goyal Return-path: Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]:61212 "EHLO ipmail04.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751903Ab1FBXqu (ORCPT ); Thu, 2 Jun 2011 19:46:50 -0400 Content-Disposition: inline In-Reply-To: <20110602141716.GD18712@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Jun 02, 2011 at 10:17:16AM -0400, Vivek Goyal wrote: > On Thu, Jun 02, 2011 at 11:22:09AM +1000, Dave Chinner wrote: > > On Wed, Jun 01, 2011 at 05:50:49PM -0400, Vivek Goyal wrote: > > > Hi, > > > > > > If I throttle a DIO/AIO WRITE bio at block device in a cgroup, will it > > > lead to any kind of serialization of ext4 file system. IOW, is there any > > > filesystem operation which will wait for that DIO/AIO WRITE to finish > > > before other filesystem can make progress (fsync, journalling etc?) > > > > Truncate? > > > > (XFS explicitly serialises truncate against in flight DIO, > > regardless of whether ext4 does.) > > > > Dave, > > Does this serialization happens against that particular inode on which > truncate has been called? If yes, then I think I will still be fine > as in common use case I am not expecting much sharing of inodes across > cgroups. Same inode serialisation only. Cheers, Dave. -- Dave Chinner david@fromorbit.com