From: Alan Cox Subject: Re: [PATCH, RFC] ext4: Use preallocation when reading from the inode table Date: Tue, 23 Sep 2008 10:16:13 +0100 Message-ID: <20080923101613.58768083@lxorguk.ukuu.org.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: "Theodore Ts'o" Return-path: Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:52315 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750899AbYIWJQh (ORCPT ); Tue, 23 Sep 2008 05:16:37 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 22 Sep 2008 20:35:23 -0400 "Theodore Ts'o" wrote: > > With modern hard drives, reading 64k takes roughly the same time as > reading a 4k block. So request adjacent inode table blocks to reduce > the time it takes when iterating over directories (especially when doing > this in htree sort order) in a cold cache case. With this patch, the > time it takes to run "git status" on a kernel tree after flushing the > caches via "echo 3 > /proc/sys/vm/drop_caches", is reduced by 21%. > > Signed-off-by: "Theodore Ts'o" Acked-by: Alan Cox I'm actually suprised that 16 is the magic tuning number you've used and a bigger one isn't even more of a win Alan