From: Jon Burgess <lkml@jburgess.uklinux.net>
To: Andrew Morton <akpm@osdl.org>
Cc: Jon Burgess <lkml@jburgess.uklinux.net>, linux-kernel@vger.kernel.org
Subject: Re: ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes
Date: Sat, 14 Feb 2004 15:00:27 +0000 [thread overview]
Message-ID: <402E380B.8070806@jburgess.uklinux.net> (raw)
In-Reply-To: <20040212015626.48631555.akpm@osdl.org>
Andrew Morton wrote:
>So you'll see that instead of a single full-bandwidth
>write, we do two half-bandwidth writes. If it weren't for disk writeback
>caching, it would be as much as 4x slower.
>
Write caching does indeed make a big difference. Here is a test run on a
drive with and without write caching (hdparm -W 0/1). The test was done
on 2.6.2 with ext3 and shows the write speed in MB/s:
Write Cache 1 Stream 2 Streams
Enabled 21.54 3.66
Disabled 18.11 0.46
The two stream case is almost 10x slower without write caching.
I don't think this explains the difference between 2.4 and 2.6 unless
one of them changes the write cache mode of the drive.
Jon
prev parent reply other threads:[~2004-02-14 15:00 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-11 19:04 ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes Jon Burgess
2004-02-11 20:28 ` Rik van Riel
2004-02-11 21:02 ` Michael Frank
2004-02-11 21:18 ` Diego Calleja
2004-02-12 2:00 ` Dave Olien
2004-02-12 2:23 ` Andrea Arcangeli
2004-02-12 9:42 ` ext2/3 performance regression in 2.6 vs 2.4 for small interl Giuliano Pochini
2004-02-12 10:15 ` John Bradford
2004-02-12 10:27 ` Nick Piggin
2004-02-12 17:05 ` Michael Frank
2004-02-12 17:18 ` Valdis.Kletnieks
2004-02-12 20:55 ` Helge Hafting
2004-02-13 1:57 ` Jamie Lokier
2004-02-13 2:05 ` Nick Piggin
2004-02-12 14:59 ` Andrea Arcangeli
2004-02-13 12:15 ` ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes Jon Burgess
2004-02-12 10:40 ` Jon Burgess
2004-02-12 20:17 ` Hans Reiser
2004-02-12 9:56 ` Andrew Morton
2004-02-12 20:20 ` Jon Burgess
2004-02-13 8:28 ` Juan Piernas Canovas
2004-02-16 17:51 ` Alex Zarochentsev
2004-02-16 20:03 ` Jon Burgess
2004-02-13 12:35 ` Jon Burgess
2004-02-14 15:00 ` Jon Burgess [this message]
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