Re: don't use wapbl (-o log) on / (/dev)

[David Holland <dholland-tech%netbsd.org@localhost>]

On Mon, Feb 16, 2009 at 07:59:25AM +0100, Reinoud Zandijk wrote:
 > > > I think the buffer cache needs to be restructured so it can be either
 > > > virtually or physically indexed. This is going to be a big hassle.
 > 
 > i think the easiest way is to make the buffer cache virtually indexed only

Doesn't really work; how do you index e.g. blocks belonging to
cylinder group summaries or the free block bitmaps or whatnot like
that?

 > since its file granularity that you want to cache on. It does not make sense
 > to cache a large file when its contents is already deleted. A Physical block
 > cache needs to exist in the discs device driver, not in a FS.

That's not really true; you want to drop/invalidate buffers for blocks
that you free when you truncate a file, and that happens regardless of
whether the cachce is virtually or physically indexed.

-- 
David A. Holland
dholland%netbsd.org@localhost