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From: fouts@bozeman.ingr.com (Martin Fouts)
Newsgroups: comp.arch
Subject: Re: Real disk FASTER than Ram disk
Message-ID: <431@garth.UUCP>
Date: 7 Jun 90 18:46:14 GMT
References: <641@sibyl.eleceng.ua.OZ> <136299@sun.Eng.Sun.COM> <1990May27.210935.8564@murdoch.acc.Virginia.EDU> <3402@auspex.auspex.com> <60196@lll-winken.LLNL.GOV> <5490@titcce.cc.titech.ac.jp>
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In-reply-to: mohta@necom830.cc.titech.ac.jp's message of 31 May 90 13:23:44 GMT

In article <5490@titcce.cc.titech.ac.jp> mohta@necom830.cc.titech.ac.jp (Masataka Ohta) writes:

   >  It's trivial to avoid the extra copy.

   Maybe. But, writing a memory disk device driver is already non-trivial.

   Moreover, a memory disk has several limitations including its maximum size.

   >  A better solution (as has been pointed out) is to allow for memory
   >resident file systems that are only written out to backing disk when
   >space is needed.

   That is what I have described in a paper titled:

	   A fast /tmp file system by delay mount option

Excuse me for disagreeing, but replacing /tmp with a file system that
gets paged isn't a good solution.  What you are doing here is working
around the lack of advance in the underlying software.  The compiler
is still writing to /tmp because it isn't managing its own address
space effectively in a virtual memory environment.  Direct mapping
files into the compiler address space and paging from that is much
more effective than using a second order paging for a "file system"
ala /tmp.

--
Martin Fouts

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If you can find an opinion in my posting, please let me know.
I don't have opinions, only misconceptions.