From owner-freebsd-hackers  Sun Sep 30  0:53:21 2001
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Date: Sun, 30 Sep 2001 00:52:54 -0700 (PDT)
From: Matt Dillon <dillon@earth.backplane.com>
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To: Vladimir Dozen <vladimir-dozen@mail.ru>
Cc: Wilko Bulte <wkb@freebie.xs4all.nl>,
	Alfred Perlstein <bright@mu.org>, hackers@FreeBSD.ORG
Subject: Re: VM: dynamic swap remapping (patch)
References: <20010929155941.A291@eix.do-labs.spb.ru> <20010929071024.Q59854@elvis.mu.org> <20010929141349.A80876@freebie.xs4all.nl> <200109291653.f8TGrRR37689@earth.backplane.com> <20010929232953.B341@eix.do-labs.spb.ru>
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:  Second, application not always grows to 1G, most of the time it keeps
:  as small as 500M ;). Why should we precommit 1G for 500M data? Doing
:  multi-mmap memory management is additional pain.

    Why not?  Disk space is cheap.  For a problem like this I would simply
    throw in two 30G+ hard drives and partition them with 16G of swap each,
    giving me 32G of swap for the machine.  If you needed to do it cheaply
    you could even use IDE, though personally I would use SCSI for 
    reliability.  Depending on the amount of real memory in the machine
    you might have to tweek a few kernel options (like matching NSWAP to
    the actual number of swap devices), but basically it should just work.

    Even using file-backed memory is fairly trivial.  You don't need to
    do multi-mmap memory management or do any kernel tweaking.  Just
    reserve 1G and use a single mmap() and file per process.

					-Matt


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