From owner-freebsd-hackers  Mon Jul 17 16:55:52 1995
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From: John Dyson <dyson>
Message-Id: <199507172355.QAA01087@freefall.cdrom.com>
Subject: Re: File cache needs lower vm priority
To: henrich@crh.cl.msu.edu (Charles Henrich)
Date: Mon, 17 Jul 1995 16:55:51 -0700 (PDT)
Cc: freebsd-hackers@freebsd.org
In-Reply-To: <199507171939.PAA03323@crh.cl.msu.edu> from "Charles Henrich" at Jul 17, 95 03:39:17 pm
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> 
> FreeBSD's merged cache needs to throw out file data at the slightest need from
> a real process.  Whenever any real I/O is going on things slow to a crawl.
> 
> -Crh
> 
The file cache is about as low in priority as it can be.  The pages
in the file cache that are not pointed to by buffers are in the
cache list.  Those pages are almost as available as free pages.  If
you have any pages in the cache list, then you should not block waiting
for memory.

It might be that the overhead for the buffer management is getting to
your machine.  I am currently working on improving the efficiency, but
on a /66 or faster the overhead should not be a killer.

John
dyson@root.com