From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Vier Subject: Re: Enable asynchronous commits by default patch revoked? Date: Wed, 2 Sep 2009 10:48:33 -0400 Message-ID: <20090902144833.GA29651@zero> References: <200908241033.10527.Christian.Fischer@easterngraphics.com> <20090824133447.GH23677@mit.edu> <20090824183119.GI5931@webber.adilger.int> <20090824201027.GC17684@mit.edu> <4A92F7E0.9010001@redhat.com> <20090824220738.GG17684@mit.edu> Reply-To: Tom Vier Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Theodore Tso Return-path: Received: from mail-px0-f204.google.com ([209.85.216.204]:54726 "EHLO mail-px0-f204.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395AbZIBOsr (ORCPT ); Wed, 2 Sep 2009 10:48:47 -0400 Received: by pxi42 with SMTP id 42so902078pxi.20 for ; Wed, 02 Sep 2009 07:48:49 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20090824220738.GG17684@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Aug 24, 2009 at 06:07:39PM -0400, Theodore Tso wrote: > Sure, agreed. But let's look a bit closer at what "async commit" > really means. > > What ext3 and ext4 does by default is this: > > 1) Write data blocks required by data=ordered mode (if any) Shouldn't there be a write barrier after data blocks, so that the journal blocks aren't written first? ie, mark the first journal block write with barrier flag on. > 2) Write the journal blocks > > 3) Wait for the journal blocks to be sent to disk. (We don't actually > do a barrier operation), so this just means the blocks have been sent > to the disk, not necessarily that they are forced to a platter. > > 4) Write the commit block, with the barrier flag set. > > 5) Wait for the commit block. -- Tom Vier DSA Key ID 0x15741ECE