From owner-freebsd-current  Mon Sep 14 02:17:23 1998
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Date: Mon, 14 Sep 1998 02:17:01 -0700 (PDT)
From: dan@math.berkeley.edu (Dan Strick)
Message-Id: <199809140917.CAA09398@math.berkeley.edu>
To: dg@root.com
Subject: Re: Download of FreeBSD 3.0-SNAP
Cc: dan@math.berkeley.edu, freebsd-current@FreeBSD.ORG
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> >FreeBSD no longer does elevator sorts on data pending output,
> >relying instead on the disk hardware to be smarter about this,
> >especially given the likelihood that the drive is lying about
> >its pysical geometry, making it unlikely that any sort you
> >could do would result in an optimization.

Even so, the driver should sort the I/O requests whenever the
system's buffer queue for the drive exceeds the capacity of
the system/host-adapter/drive for concurrently active commands.
Since actual drive "geometry" is usually messy these days,
a simple minded sort by block number would be appropriate.

Dan Strick
dan@math.berkeley.edu

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