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Date:      Fri, 7 May 1999 09:46:10 -0700 (PDT)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        Chris Costello <chris@holly.dyndns.org>
Cc:        "Ronald G. Minnich" <rminnich@acl.lanl.gov>, hackers@FreeBSD.ORG
Subject:   Re: memory-based VFS
Message-ID:  <199905071646.JAA45627@apollo.backplane.com>
References:  <Pine.SGI.4.10.9905070807550.511395-100000@acl.lanl.gov> <19990507092008.A580@holly.dyndns.org>

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:On Fri, May 7, 1999, Ronald G. Minnich wrote:
:> The v9fs memory-based VFS, written by Aaron Marks, is available at
:> http://www.acl.lanl.gov/~rminnich/
:
:   Doesn't this do the same thing as MFS?

    Not to detract from the cool things people have been writing, but 
    in FreeBSD-current, it is possible to directly swap-back the VN device 
    and mount a softupdates-enabled filesystem over it.  You effectively get
    a memory filesystem due to the way the standard VM cache works.  MFS is
    also a memory filesystem, but MFS wastes memory because the data 
    representing a block exists in two places ( non-shared ) - the MFS
    process's VM space, and in the system VM cache.  With the VN device, you
    wind up with more swap activity but ( probably ) better VM management -
    it doesn't starve memory and force defensive paging like MFS does.

    There are some very cool things coming down the pipe in the next 6 months.
    Poul has some excellent ideas on how to fix the VFS/BIO I/O subsystem.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>

:> This is intended to serve as the basis of private name spaces for FreeBSD.
:> I have a VFS and full implementation for Linux kernel 2.0.x, soon to go on
:> the web page too.
:> 
:> Anyone who'd like to talk to me about private name spaces for freebsd,
:> give me a ring. 
:> 
:> ron
:-- 
:Chris Costello                                <chris@calldei.com>
:Me and my two friends... GIF and Wesson.



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