Linux SCSI subsystem development
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From: Andrew Morton <akpm@digeo.com>
To: James Bottomley <James.Bottomley@steeleye.com>
Cc: linux-scsi@vger.kernel.org, Jens Axboe <axboe@suse.de>
Subject: Re: Possible explanation for SCSI benchmark problems in 2.5
Date: Sun, 29 Sep 2002 13:53:56 -0700	[thread overview]
Message-ID: <3D976864.65C82D7B@digeo.com> (raw)
In-Reply-To: 200209292048.g8TKmN424799@localhost.localdomain

James Bottomley 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.
> 

argh, sorry.  I've had such a patch in my tree for ages, and
I do all testing with it in place.

But high-IO is bust for IDE as well at present, so at least
we're being fair ;)

  reply	other threads:[~2002-09-29 20:53 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 [this message]
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
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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