From: Andrew Morton <akpm@osdl.org>
To: Rene Herman <rene.herman@gmail.com>
Cc: Tejun Heo <htejun@gmail.com>, Jens Axboe <axboe@suse.de>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>
Subject: Re: 2.6.20-rc2+: CFQ halving disk throughput.
Date: Mon, 1 Jan 2007 21:36:01 -0800 [thread overview]
Message-ID: <20070101213601.c526f779.akpm@osdl.org> (raw)
In-Reply-To: <45998F62.6010904@gmail.com>
On Mon, 01 Jan 2007 23:46:58 +0100
Rene Herman <rene.herman@gmail.com> wrote:
> > Everything seems fine in the dmesg. Performance degradation is
> > probably some other issue in -rc kernel. I'm suspecting recently
> > fixed block layer bug. If it's still the same in the next -rc,
> > please report.
>
> In fact, it's CFQ. The PATA thing was a red herring. 2.6.20-rc2 and 3
> give me ~ 24 MB/s from "hdparm t /dev/hda" while 2.6.20-rc1 and below
> give me ~ 50 MB/s.
>
> Jens: this is due to "[PATCH] cfq-iosched: tighten allow merge
> criteria", 719d34027e1a186e46a3952e8a24bf91ecc33837:
>
> http://www2.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=719d34027e1a186e46a3952e8a24bf91ecc33837
>
> If I revert that one, I have my 50 M/s back. config and dmesg attached
> in case they're useful.
The patch would appear to need this fix:
--- a/block/cfq-iosched.c~a
+++ a/block/cfq-iosched.c
@@ -592,7 +592,7 @@ static int cfq_allow_merge(request_queue
if (cfqq == RQ_CFQQ(rq))
return 1;
- return 1;
+ return 0;
}
static inline void
_
But that might not fix things...
next prev parent reply other threads:[~2007-01-02 5:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-20 13:37 PATA -- pata_amd on 2.6.19 fails to IDENTIFY my DVD-ROM Rene Herman
2006-12-27 7:19 ` Tejun Heo
2006-12-27 17:50 ` Rene Herman
2006-12-28 2:24 ` Tejun Heo
2007-01-01 22:46 ` 2.6.20-rc2+: CFQ halving disk throughput Rene Herman
2007-01-01 22:56 ` Rene Herman
2007-01-01 23:30 ` Linus Torvalds
2007-01-01 23:28 ` Mark Lord
2007-01-02 8:34 ` Jens Axboe
2007-01-02 15:01 ` Mark Lord
2007-01-02 16:53 ` Tejun Heo
2007-01-02 17:35 ` Mark Lord
2007-01-02 17:53 ` Tejun Heo
2007-01-02 18:10 ` Mark Lord
2007-01-02 21:50 ` ATA_12 support for libata/ATAPI devices Mark Lord
2007-01-02 17:09 ` 2.6.20-rc2+: CFQ halving disk throughput Jan Engelhardt
2007-01-02 5:36 ` Andrew Morton [this message]
2007-01-02 8:44 ` Jens Axboe
2007-01-02 10:24 ` Rene Herman
2007-01-02 11:57 ` Jens Axboe
2007-01-02 12:10 ` Jens Axboe
2007-01-02 15:12 ` Mark Lord
2007-01-02 15:14 ` Jens Axboe
2007-01-02 15:40 ` Mark Lord
2007-01-02 15:45 ` Jens Axboe
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