From owner-freebsd-questions  Wed Nov 28  0:33:10 2001
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Date: Wed, 28 Nov 2001 10:32:52 +0200
From: Giorgos Keramidas <charon@labs.gr>
To: Anthony Atkielski <anthony@freebie.atkielski.com>
Cc: questions@FreeBSD.ORG
Subject: Re: Calculating swap file size
Message-ID: <20011128083251.GD1844@hades.hell.gr>
References: <15363.24098.8617.782371@guru.mired.org> <006101c17728$2fdfae30$0a00000a@atkielski.com>
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On 2001-11-27 10:45:01, Anthony Atkielski wrote:
> The FAQ says:
>
> "Note that while FreeBSD is proactive in this regard [swapping pages out in
> anticipation of a need for memory], it does not arbitrarily decide to swap pages
> when the system is truly idle."
>
> As far as I can tell, my lightly loaded system never uses the swap file at all:
>
> freebie# swapinfo
> Device          1K-blocks     Used    Avail Capacity  Type
> /dev/ad0s1b        819072        0   819072     0%    Interleaved
>
> So it would appear that the swap file is not touched below some threshold of
> system activity.

Well, not quite so.  On my lightly' loaded machine, that runs a few
services that are rarely (if ever) used, swap *is* being used:

    $ uptime
    10:29AM  up  2:52, 1 user, load averages: 0.17, 0.32, 0.50
    $ swapinfo
    Device          1K-blocks     Used    Avail Capacity  Type
    /dev/ad0s1b       1048448     5560  1042888     1%    Interleaved

Understanding how the virtual memory subsystem works in FreeBSD is a bit out of
my reach right now, but I think that it will swap out idle processes after a
while.  Perhaps I'm wrong...

-giorgos

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