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Date:      Fri, 9 Aug 1996 10:40:57 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        joerg_wunsch@uriah.heep.sax.de
Cc:        freebsd-hackers@FreeBSD.org, rminnich@Sarnoff.COM
Subject:   Re: "Panick" - help needed...
Message-ID:  <199608091740.KAA19017@phaeton.artisoft.com>
In-Reply-To: <199608090547.HAA02326@uriah.heep.sax.de> from "J Wunsch" at Aug 9, 96 07:47:57 am

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> > If anyone runs this on a freebsd desktop i'd be interested in what you 
> > observe -- how does interactive response function as this program runs. 
> 
> About the same as you observed on Linux.  As i wrote in the other
> mail, i had to force a `top' to get CPU cycles using `rtprio'.

The problem appears (from a first perusal of the code) that the cache
is being thrashed.

The need to be able to support a per vnode working set quota on page
usage by:

1)	reclaiming in a local LRU
2)	inserting pages reclaimed from this LRU overflow at the *head*
	of the free pool LRU so that it will be the next to be reused.

This should move the locality from global to per vnode, and prevent
a given vnode from monopolizing the available pages from a single
process instead of preserving other processes locality.

This technique was used to great effect on a UnixWare 2.x I had hacked
to resolve the fact that ld mmap'ed a bunch of files and thrashed the
hash to the point where the X server failed to move the cursor when
you moved the mouse.  Unfortuantely, my changes were ignored, and they
implemented a "fixed" scheduling class instead -- their solution, which
I must say, doesn't fix the problem.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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