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Date:      Mon, 1 Apr 1996 13:07:59 -0500 (EST)
From:      "John S. Dyson" <toor@dyson.iquest.net>
To:        luigi@labinfo.iet.unipi.it (Luigi Rizzo)
Cc:        lehey.pad@sni.de, joerg_wunsch@uriah.heep.sax.de, freebsd-hackers@FreeBSD.ORG
Subject:   Re: Virtual Memory system (was: Interesting IDE perf results)
Message-ID:  <199604011807.NAA17963@dyson.iquest.net>
In-Reply-To: <199604011557.RAA23477@labinfo.iet.unipi.it> from "Luigi Rizzo" at Apr 1, 96 05:57:57 pm

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> 
> Note that 1.1.5 has no unusual settings, while the 2.1R  has been
> patched with phkmalloc, custom-built XF86_SVGA with only the minumum
> set of drivers, no unused servers etc. Both systems have custom,
> stripped down kernels.  The same symptoms, though less evident,
> occurs on a system with 16MB.
> 
> Is it just me ?
> 
The system does let go of not recently used pages more quickly when
someone else needs them.  The algorithm is based heavily on recent usage
stats.  It can converge very quickly to a small working set.  I think that
part of the problem is that we don't start gathering stats until we are
out of memory.  I have some changes to the pageout daemon that would be
interesting to try if you want.  (I am only working on -current though.)
For a quick hack (might not work,) you might try changing the tsleep in the
mainloop of the pageout daemon (vm_pageout) so that it wakes up every half
second or so.  (Put a 60 in the last arg that is currently a 0.)  Tell me how
it works.

John




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