Subject: Re: Disk scheduling policy (Re: NEW_BUFQ_STRATEGY)
To: None <email@example.com>
From: Jason Thorpe <firstname.lastname@example.org>
Date: 12/01/2003 15:16:40
-----BEGIN PGP SIGNED MESSAGE-----
On Dec 1, 2003, at 3:11 PM, Thor Lancelot Simon wrote:
> Matt Thomas suggested simply starting at whichever end of the other
> queue is nearer the current head position, which is an interesting
> idea. I was pondering zoning the disk, so you'd have multiple "queues"
> on each side of the "delayed"/"normal" divide, and could try to switch
> to the one nearest the block you're currently at, but that adds
> significant complexity. I'm going to implement a couple of different
> things and measure them for different workloads.
Presumably this would imply recording the block # of the last request
that was issued on the disk?
I can see a danger in this kind of algorithm... if you were to always
prefer issuing requests for "near by" blocks, then you could get into a
situation where an app that performs many transactions to a localized
region could starve other apps whose data is "somewhere else".
-- Jason R. Thorpe <email@example.com>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (Darwin)
-----END PGP SIGNATURE-----