[7936] in linux-scsi channel archive
Re: request merge changes?
daemon@ATHENA.MIT.EDU (Jens Axboe)
Tue Jan 25 20:58:09 2000
Date: Tue, 25 Jan 2000 17:01:40 +0100
From: Jens Axboe <axboe@suse.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Eric Youngdale <eric@andante.org>, linux-scsi@vger.rutgers.edu
Message-ID: <20000125170140.A2016@suse.de>
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In-Reply-To: <E12D888-0008HR-00@the-village.bc.nu>; from alan@lxorguk.ukuu.org.uk on Tue, Jan 25, 2000 at 03:43:43PM +0000
On Tue, Jan 25 2000, Alan Cox wrote:
> > max_segments which, again, is a per-major kind of thing. Has anyone
> > experimented with setting this higher? The DAC960 is currently
> > the only driver manipulating it. The default value is indeed 128
> > sectors, or 64KB.
>
> We can't. its per major. But the scsi layer does its own request merging
> too (clustering code).
Sure, but as I see it the scsi layer will never attempt to cluster
requests larger than what the ll_rw_block currently permits (without
help).
I do like the idea of having devices control their own merging,
it allows for greater flexibility. But current 2.3 is just not
very clear on what is handled by ll_rw_block and what the devices
do themselves.
--
* Jens Axboe <axboe@suse.de>
* Linux CD-ROM Maintainer
* http://www.kernel.dk
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