Subject: Re: New FFS Layout: Update or fresh install?
To: Greywolf <firstname.lastname@example.org>
From: David Brownlee <email@example.com>
Date: 08/09/2002 16:43:32
On Tue, 6 Aug 2002, Greywolf wrote:
> On Tue, 6 Aug 2002, David Brownlee wrote:
> # In 1.5.2 and earlier the default FFS blocksize is 8K, and
> # fragments 16K.
> Really?? Fragment sizes are larger than block sizes??
> This should have some interesting results on my filesystems.
Thanks for picking up the typo :) - should have been 1K.
> # This is in addition to the obvious softdep and other improvements,
> # and in 1.6 UBC and other wins :)
> Heh. I was happy to see Chuq still whittling away at UBC, noting that it
> still has a few small problems. So often, I've seen an attitude (on other
> projects) with new subsystems or whatnot that has been "Well, there it is.
> It's not bug-ridden, that's the way it's meant to work. Deal with it," even
> when its performance is horrid. UBC will likely be a work in progress for
> quite some time...
The biggest problem I've seen with UBC is that it lets the
machine efficiently use a large quantity of memory for
filesystem caching. This is only a problem because it shows
up a deficiency in the disk sorting algorithm. You could
see the problem in earlier NetBSD versions, but it was
harder to trigger. I believe work is under way on this issue.
David/absolute -- www.netbsd.org: No hype required --