Subject: Re: disk caching
To: Mirian Crzig Lennox <>
From: Frank van der Linden <>
List: tech-kern
Date: 04/12/2000 17:40:36
On Wed, Apr 12, 2000 at 11:01:17AM -0400, Mirian Crzig Lennox wrote:
> So I've noticed that linux seems to be able to fudge a heck of a lot
> of disk io performance from just throwing huge amounts of cache at the
> problem.  Although inelegant, this approach really does seem to move
> disk io right along.  I'm wondering if the same effect can be duplicated
> in NetBSD, or if NetBSD has an even better approach to the problem.

Linux' buffer cache grows and shrinks with the availability of memory,
i.e. it's dynamically sized.

NetBSD's buffer cache currently is still fixed size, however, post-1.5,
Chuck Silvers' UBC work will be brought into the tree, which makes
our buffer cache also use more memory if it's available. And it
solves the "mmap() doesn't see what write() does and vice versa" problem
(hence it's name, Unified Buffer Cache).

The static size of the buffer cache can currently be controlled
by the "BUFCACHE" option, which is a percentage of available memory.

- Frank