From: Mike Anderson <andmike@us.ibm.com>
To: James Bottomley <James.Bottomley@steeleye.com>
Cc: linux-scsi@vger.kernel.org, Andrew Morton <akpm@digeo.com>,
Jens Axboe <axboe@suse.de>
Subject: Re: Possible explanation for SCSI benchmark problems in 2.5
Date: Sun, 29 Sep 2002 14:32:46 -0700 [thread overview]
Message-ID: <20020929213246.GA3743@beaverton.ibm.com> (raw)
In-Reply-To: <200209292048.g8TKmN424799@localhost.localdomain>
James Bottomley [James.Bottomley@steeleye.com] wrote:
> Hi All,
>
> While looking at other code (OK, how to get the MCA drivers not to use bounce
> buffers...) I discovered that the way scsi_scan.c calls
> scsi_initialize_merge_fn() guarantees (on an x86) that the
> blk_queue_bounce_limit is always called with BLK_BOUNCE_HIGH. This will
> probably hurt benchmarks on machines with 1Gb or more of memory.
>
> The problem is that scsi_initialize_merge_fn() checks sdev->type, but this is
> always -1 in scsi_alloc_sdev, and thus it never uses the pci dma mask for disk
> devices.
>
> The attached patch moves the initialisation to after sdev->type has the
> correct value.
I thought this was previously discussed on this thread.
http://marc.theaimsgroup.com/?l=linux-kernel&m=103064539622958&w=2
and I believe the comment from Jens was that this could be killed
off in 2.5 if someone did a check for safety on all the devices.
-andmike
--
Michael Anderson
andmike@us.ibm.com
next prev parent reply other threads:[~2002-09-29 21:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-29 20:48 Possible explanation for SCSI benchmark problems in 2.5 James Bottomley
2002-09-29 20:53 ` Andrew Morton
2002-09-30 7:30 ` Jens Axboe
2002-09-30 7:46 ` Andrew Morton
2002-09-30 7:47 ` Jens Axboe
2002-09-29 21:32 ` Mike Anderson [this message]
2002-09-30 3:40 ` James Bottomley
2002-09-30 6:15 ` Kai Makisara
2002-09-30 7:32 ` Jens Axboe
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