Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!news.ecn.uoknor.edu!solace!nntp.uio.no!Norway.EU.net!EU.net!news.eunet.fi!news.spb.su!satisfy.kiae.su!Gamma.RU!srcc!newsserv
From: "Eugene Radchenko" <eugene@qsar.chem.msu.su>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: MFS - Why?
Date: 5 Jun 1996 18:00:44 +0400
Organization: Lab. of Org.Synth., MSU
Lines: 35
Distribution: world
Message-ID: <ABgvNUrSgM@qsar.chem.msu.su>
References: <4ogp99$kfu@nntp5.u.washington.edu>
Reply-To: eugene@qsar.chem.msu.su
NNTP-Posting-Host: crocus.gamma.ru
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Return-Path: qsar!qsar.chem.msu.su!eugene@gamma.srcc.msu.su
In <4ogp99$kfu@nntp5.u.washington.edu> kargl@hotrat.apl.washington.edu (kargl@hotrat.apl.washington.edu) wrote:
> "Eugene Radchenko" <eugene@qsar.chem.msu.su> wrote in article <AEn4jRr0u3@qsar.chem.msu.su> :
> >I could not figure this out myself. What is the point of using MFS
> >(especially for the temporary files) if the system has disk caching
> >(especially merged VM/disk cache like FreeBSD)?
> >In fact, SGI FAQ spanks the idea of RAM disk under Unix as a PC-ism and
> >claims that kernel does a much better job of figuring what to keep where if
> >you just copy something to normal filesystem.
> >Could you knowledgeable folks shed some light on this?
>
> Because many programs will create temporary files. Try compiling a C
> program without the -pipe option and with the -v option. You'll see a
> few temporary files created. Writing these temporary files to a MFS
> is much faster than writing to disk. Of course, if you have the memory
> available for a MFS, you'll want to use the -pipe option with gcc.
I guess I was not sufficiently clear in the original posting. If we have
merged disk cache/VM buffer and we open a file and write something to it,
then the data end up into that same buffer area as they would if we create
a file on the memory filesystem (with a difference that they could be
'paged out' to normal filesystem if someone needs heaps of memory while the
MFS data could not). So what is the point?
Bye Genie
--
-----------------------------------------------------------------------
Eugene V. Radchenko Research associate, Computer Chemistry
E-mail: eugene@qsar.chem.msu.su Fax: +7-(095)939-0290
Ordinary mail: Chair of Organic Chemistry, Department of Chemistry,
Moscow State University, 119899 Moscow, Russia
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Axiom: Any non-trivial program contains some bugs
Corollary: If a program has no bugs, it is useless