Date: Tue, 15 Sep 1998 20:06:18 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: mike@smith.net.au (Mike Smith) Cc: dg@root.com, tlambert@primenet.com, joelh@gnu.org, tom@uniserve.com, gpalmer@FreeBSD.ORG, irc@cooltime.simplenet.com, freebsd-current@FreeBSD.ORG Subject: Re: Download of FreeBSD 3.0-SNAP Message-ID: <199809152006.NAA22649@usr09.primenet.com> In-Reply-To: <199809150940.CAA00565@word.smith.net.au> from "Mike Smith" at Sep 15, 98 02:40:05 am
next in thread | previous in thread | raw e-mail | index | archive | help
> I don't think anyone would disagree with this; my point was simply that > disks are effectively nondeterministic, so by definition you can't have > an "optimal" solution. Bull. Hardware and software are no more non-deterministic than neutron numbers or when sunrise will occur. > I've seen assorted drive literature describing different caching > policies on modern drives, and I think it's probably in our interest > not to try too hard to outsmart the disk these days, as it's busy > trying to outsmart us. This isn't a very valid argument. If it wre, we should agressively discard cached pages in main memory, on the theory that the disk controller knows better than we do what pages we will need next. There is such a thing as locality of reference, which has nothing to do with locality of disk blocks within a contiguous set of blocks. This is the primary reason why the correct thing to do about the ports tree is a breadth-first restore from a depth-first archive. > If you really wanted to play games with the queue sorter, you might > want to go for a minimal distance insertion policy rather than a strict > ladder sort. As Kirk pointed out, there's plenty of room for > experimentation in this field. 8) Actually, much of this has already been covered in the literature in the 17 years between 1981 and now... Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199809152006.NAA22649>