Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!bostic
From: bostic@ucbvax.BERKELEY.EDU (Keith Bostic)
Newsgroups: comp.unix.wizards
Subject: Re: /dev/swap - possibility of it being a ramdisk
Keywords: /dev/swap
Message-ID: <22157@ucbvax.BERKELEY.EDU>
Date: 13 Dec 87 19:44:25 GMT
References: <712@qetzal.UUCP>
Organization: University of California at Berkeley
Lines: 28

In article <712@qetzal.UUCP>, rcw@qetzal.UUCP (Robert C. White) writes:
> Watching my poor little unix boxes swap, it occurred to me:
> why not utilize some extra ram to implement /dev/swap?

The idea is to get all the memory you can and put the file systems that you
use for small, temporary file creation in memory.  Not /dev/swap, as enough
memory means never having to say you're swapping.

In article <10796@brl-adm.ARPA>, mike@BRL.ARPA (Mike Muuss) writes:
> BRL gave a lot of business to the "BULK MOS" RF-11 emulator companies
> back in the PDP-11 days.  It was indeed true that the best choice
> for a bulk memory system was /tmp.  The second best choice was the
> root itself.

This (root as RAM being good) was really a problem with the V7 kernel.  Since
the V7 kernel immediately discarded all text segments and inodes (until Mike
Karels added shared text segments to 2.9BSD, whereupon it discarded them
after the last reference disappeared) it helped to put the program in a RAM
disk.  The real fix was to teach the kernel to do LRU cacheing on the text
and inodes.

Once that was done, we found that, on PDP's with 4MB of memory and student
type loads, you can't get enough people on the machine to use all of memory
and nothing ever swaps.

Keith Bostic
ARPA:	bostic@okeeffe.berkeley.edu
UUCP:	ucbvax!bostic or seismo!keith