From: Adrian Hunter Subject: [PATCH 0/2] ext3 HACKs Date: Tue, 14 Jul 2009 17:02:53 +0300 Message-ID: <20090714140253.25993.64525.sendpatchset@ahunter-tower> Cc: Artem Bityutskiy , linux-ext4@vger.kernel.org, Adrian Hunter To: Andrew.Morton.akpm@linux-foundation.org, Andreas.Dilger.adilger@sun.com, Stephen.Tweedie.sct@redhat.com Return-path: Received: from smtp.nokia.com ([192.100.122.230]:53459 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752744AbZGNOAc (ORCPT ); Tue, 14 Jul 2009 10:00:32 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi We are using linux 2.6.28 and we have a situation where ext3 can take 30-60 seconds to mount. The cause is the underlying device has extremely poor random write speed (several orders of magnitude slower than sequential write speed), and journal recovery can involve many small random writes. To alleviate this situation somewhat, I have two moderately ugly hacks: HACK 1: ext3: mount fast even when recovering HACK 2: do I/O read requests while ext3 journal recovers HACK 1 uses a I/O barrier in place of waiting for recovery I/O to be flushed. HACK 2 crudely throws I/O read requests to the front of the dispatch queue until the I/O barrier from HACK 1 is reached. If you can spare a moment to glance at these hacks and notice any obvious flaws, or suggest a better alternative, it would be greatly appreciated. Regards Adrian Hunter