From owner-freebsd-questions  Tue Mar 19 00:45:20 1996
Return-Path: owner-questions
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id AAA14760
          for questions-outgoing; Tue, 19 Mar 1996 00:45:20 -0800 (PST)
Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5])
          by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id AAA14738
          for <questions@FreeBSD.ORG>; Tue, 19 Mar 1996 00:44:14 -0800 (PST)
Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id JAA02248; Tue, 19 Mar 1996 09:35:10 +0100
From: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
Message-Id: <199603190835.JAA02248@labinfo.iet.unipi.it>
Subject: Re: Diskless FreeBSD
To: msmith@atrad.adelaide.edu.au (Michael Smith)
Date: Tue, 19 Mar 1996 09:35:10 +0100 (MET)
Cc: amigus@cs.mun.ca, questions@FreeBSD.ORG
In-Reply-To: <199603190627.QAA29799@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Mar 19, 96 04:57:05 pm
X-Mailer: ELM [version 2.4 PL23]
Content-Type: text
Sender: owner-questions@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

> Make sure you preallocate the swapfile.

Does anyone know *why* is it necessary to preallocate the swap ? I
believe it wasn't necessary back in 1.1 times.

I am asking because I plan to support diskless for our lab (50+
systems, but very few of them are expected to be in use simultaneously),
and preallocating some 20MB of swap for each machine seems unnecessary
expensive.

I am currently working on the netboot code, so I am open to suggestions.
I'd like to implement code to reset the swap file to size 0 before
transferring control to the kernel, or, if preallocation is really
necessary, I'd rather create a file with a unique big hole of
appropriate size, so that it does not occupy disk space when not
necessary.

	Luigi
====================================================================
Luigi Rizzo                     Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it       Universita' di Pisa
tel: +39-50-568533              via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522              http://www.iet.unipi.it/~luigi/
====================================================================