Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: watmath!myrias!brb@uunet.uu.net (Brian Baird)
Newsgroups: comp.sys.sun
Subject: Re: more disk buffers under 3.x?
Keywords: SunOS
Message-ID: <3640@kalliope.rice.edu>
Date: 5 Jun 89 15:08:04 GMT
Sender: usenet@rice.edu
Organization: Sun-Spots
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Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 8, Issue 13, message 3 of 17

> Those are some pretty damn small buffers!  Does anyone know a way to make
> this REALLY work (and DON'T say "yeah, upgrade to 4.0" and use the dynamic
> buffer allocation)?  My server is sitting here with 8Mb of memory, only
> 3Mb of which have a chance of being used (that is the typical VIRTUAL
> memory usage of the server).  Any help would be greatly appreciated.

The trick to increasing the number of buffers in SunOS 3.X (and in 4BSD
systems in general) is that there are two variables:  "nbuf" and
"bufpages".  Ordinarily both of these are 0.  A zero value of nbuf means
use up as many bufpages as it can.  A zero value for bufpages means that
bufpages takes up about 10% of memory.  On a 8MB 3/280, this ends up as
bufpages of 95 (8KB pages).

Increasing "nbuf" will not end up doing anything unless "bufpages" is also
changed.  In fact, the simplest course of events is to just change
"bufpages".

	% adb -w /vmunix
	bufpages?W 0t700
	^D
will change vmunix to use 700 buffers (5.4MB!) on the next reboot.
 
Brian Baird			brb@myrias.uucp
Myrias Research, Edmonton	uunet!ubc-cs!alberta!myrias!brb