Date: Thu, 27 Feb 2003 11:31:19 -0800 From: David Schultz <das@FreeBSD.ORG> To: Paul Robinson <paul@iconoplex.co.uk> Cc: hiten@unixdaemons.com, hackers@FreeBSD.ORG Subject: Re: Disk scheduling in FreeBSD Message-ID: <20030227193119.GA37891@HAL9000.homeunix.com> In-Reply-To: <IPEDKJGCDFHOPEFKLIDHIEPMCCAA.paul@iconoplex.co.uk> References: <1046361700.3e5e3664bcf24@webmail.unixdaemons.com> <IPEDKJGCDFHOPEFKLIDHIEPMCCAA.paul@iconoplex.co.uk>
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Thus spake Paul Robinson <paul@iconoplex.co.uk>: > Hiten Pandya wrote: > > > Hello gang. > > > > Does anyone know what kind of `Disk Scheduling' algorithm, > > if any, is used in FreeBSD? > > I'm assuming you've read this recently then: > > http://www.kerneltrap.org/node-592.html ... > Anybody else got plans on this? I need to have a proper look around the > source tree, but I think this would be both self-contained (i.e. easy to > back out if it breaks) and useful. Quite a small-ish project really as well. The original anticipatory scheduler implementation was done for FreeBSD 4.3. See http://www.cs.rice.edu/~ssiyer/r/antsched/ I haven't looked carefully at it myself; I've only heard about it through someone who knows Margo Seltzer. It looks very interesting, although I worry that it would interfere with the prefetching and sequential heuristics that the VM system already does (which are already VERY good[1]). Maybe the authors already thought of that issue and addressed it. So in short, I don't know much about it, but I think it's worth looking into. [1] The fact that the improvement Linux got out of the new approach was so much greater than the improvement FreeBSD 4.3 got out of it is a testament to that fact, I think. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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