Subject: Re: Increasing buffer cache?
To: Andrew Gillham <>
From: Chris G Demetriou <Chris_G_Demetriou@LAGAVULIN.PDL.CS.CMU.EDU>
List: current-users
Date: 01/22/1995 22:06:47
> I have a NetBSD machine that I am using as an NFS server, and
> I would like to increase the size of the buffer cache beyond
> the normal amount.  I have 32MB and would like to increase the
> cache from the 1.7MB it is now to between 8-12MB.  Is this possible?
> Recommended?  I tried using "options NBUF=4096", but that doesn't
> seem to be it.

compiling with NBUF=4096 will get you more buffers (i.e. the _header_
structures) but not more buffer pages.

what you probably want is more like:

options BUFPAGES=4096

which would get you 4096 pages of buffers (i.e. 16M of buffers)

you can get rid of the NBUF line, too, unless you want that
specifically set to 4096 (actually, by default, nbuf will be set to
the number of buffer pages you have allocated).

i'd say that if you're running a server, you should be running:
	(1) file systems that are at least 8k block size,
	(2) lots of buffer pages,
	(3) nbuf = bufpages / (8k / PAGE_SIZE).

i.e. if you want 16M of buffer cache on the following types of
machines, for use in a file server, i'd reccomend:

page size:			buf. pgs for 16M	# of buffers
				(i.e BUFPAGES)		(i.e. NBUF)
4k (i386, hp300, etc.)		4096			2048
8k (other m68k ports, etc.)	2048			2048

i'm not sure where the sparcs fit in there, nor the pmax, etc.

that's assuming 8k file systems, of course...