From: Theodore Tso Subject: Re: [Q] ext3 mkfs: zeroing journal blocks Date: Tue, 12 May 2009 17:04:46 -0400 Message-ID: <20090512210446.GD23773@mit.edu> References: <71a0d6ff0905110803t1a6b34ccq91d5494f95fe1f34@mail.gmail.com> <4A086763.9090907@redhat.com> <20090511182050.GA3209@webber.adilger.int> <4A087202.4010601@redhat.com> <71a0d6ff0905120455x291d7280ybe8d1a562987fd1b@mail.gmail.com> <20090512121305.GL21518@mit.edu> <71a0d6ff0905120549h628146d8p3def31b09b79199a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , Andreas Dilger , linux-ext4@vger.kernel.org To: Alexander Shishkin Return-path: Received: from THUNK.ORG ([69.25.196.29]:46060 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752194AbZELVEu (ORCPT ); Tue, 12 May 2009 17:04:50 -0400 Content-Disposition: inline In-Reply-To: <71a0d6ff0905120549h628146d8p3def31b09b79199a@mail.gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, May 12, 2009 at 03:49:30PM +0300, Alexander Shishkin wrote: > > So, what Andreas explained yesterday also applies to the internal log > case. I see. Would you say it's possible to prevent this, for instance > somehow say, by means checksums as Andreas suggested? > It's *possible*, but it's not a trivial amount of work; it requires both kernel and userspace changes, though. > It's an mmc and it (mkfs) runs almost two times faster without zeroing > the journal. The only thing I'm worried about is the time that it > takes for mke2fs -j to complete. I've done some caching trickery to > unix_io.c which I'm going to post here separately, but most of the > time seems to be taken by the journal. But why do you care about the time it akes for mke2fs -j to complete? How much time is it taking? Normally mke2fs isn't one of those programs which gets run all the time.... - Ted