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From: Jeremy Higdon <jeremy@sgi.com>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: mpm@waste.org, SCSI Mailing List <linux-scsi@vger.kernel.org>
Subject: Re: [RFC] Make the SCSI mempool allocations variable
Date: Tue, 9 Mar 2004 22:21:20 -0800	[thread overview]
Message-ID: <20040310062120.GN148048@sgi.com> (raw)
In-Reply-To: <1078858977.1756.40.camel@mulgrave>

On Tue, Mar 09, 2004 at 02:02:55PM -0500, James Bottomley wrote:
> Based on Jeremy's request to increase max_phys_segments, this is the way
> to do it (SCSI_MAX_PHYS_SEGMENTS) is the value that gets set as the
> queue's max_phys_segments.
> 
> I have to say that when I tried raising it to 256 and hammering a 10GB
> ext2 filesystem, I still didn't generate any >128 segment requests, so
> I'm dubious that raising it has any benefit at all, but feel free to try
> it and publish the figures.
> 
> I did wonder if lowering it might help improve the memory footprint for
> some embedded systems, so I set it up to be lowered as far as 32.
> 
> James

Thanks, James!

I promise that we will take advantage of this, but it might take a
couple of months.  As you point out, the filesystem code also has
to deliver the larger requests.

I'll try a couple of tests with XFS and block device direct I/O.

jeremy

  reply	other threads:[~2004-03-10  6:21 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-03-09 19:02 [RFC] Make the SCSI mempool allocations variable James Bottomley
2004-03-10  6:21 ` Jeremy Higdon [this message]
2004-03-10 10:07 ` Jeremy Higdon
2004-03-10 15:29   ` James Bottomley
2004-03-11  6:38     ` Jeremy Higdon

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