Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!metro!munnari.OZ.AU!spool.mu.edu!usenet.eel.ufl.edu!bofh.dot!arclight.uoregon.edu!news.uoregon.edu!vixen.cso.uiuc.edu!newsfeed.internetmci.com!in1.uu.net!news.artisoft.com!usenet
From: Terry Lambert <terry@lambert.org>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Linux vs. FreeBSD ... (FreeBSD extremely mem/swap hungry)
Date: Sat, 25 May 1996 16:14:16 -0700
Organization: Me
Lines: 36
Message-ID: <31A79448.3915316B@lambert.org>
References: <3188C1E2.45AE@onramp.net> <4mnsc5$6qo@sundial.sundial.net> <4mr1pk$cdi@dyson.iquest.net> <4n0dhd$cff@agate.berkeley.edu> <3194622D.41C67EA6@Ami-chan.res.cmu.edu> <31A52667.794BDF32@zeus.co.uk>
NNTP-Posting-Host: hecate.artisoft.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mailer: Mozilla 2.01 (X11; I; Linux 1.1.76 i486)
Damian Reeves wrote:
] Your damm right they do! I think the FreeBSD developer's
] are subsidised by ram and harddrive manufactures.
[ ... ]
] On replacing with BSD, and copying over the .xsession files
] etc., by the time the Xserver and xterms have started, 50MB
] of swap is in use!!! I had to increase the swap space up to
] 250Mb just so we could actually compile our server code. At
] the moment, the machine is sitting there with 1 user logged
] in, emacs, netscape and a couple of shells. top reports that
] 59% of the swap space is in use! top also reports that
] only 860k is available for buffer cache, in fact I've never
] seen it go over 1200k. This is extremely different to under
] linux, where it used to stay around 12Mb-15Mb under use.
]
] Now, one has to ask WHY?
Because you are misinterpreting "used swap" as "swap containing
dirty pages".
Linux discards clean pages. FreeBSD preferentially caches them
because it knows that the vnode pager is slower than the swap
pager.
It's a pretty obvious speed optimization that doesn't really
increase the number of dirty pages in swap over that of Linux,
but drastically increases page-in speed.
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.