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From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199610031312.IAA00602@dyson.iquest.net>
Subject: Re: vnode and cluster read-ahead
To: dfr@render.com (Doug Rabson)
Date: Thu, 3 Oct 1996 08:12:30 -0500 (EST)
Cc: dyson@freebsd.org, phk@critter.tfs.com, heo@cslsun10.sogang.ac.kr,
        freebsd-hackers@freebsd.org, freebsd-fs@freebsd.org
In-Reply-To: <Pine.BSF.3.95.961003102610.10204O-100000@minnow.render.com> from "Doug Rabson" at Oct 3, 96 10:35:19 am
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> 
> On the subject of saving memory, I firmly believe that signficant
> performance improvements can be made just by reducing the memory footprint
> of algorithms.  In our 3D graphics work, we have found that making
> important datastructures fit into cache lines (and using an aligning
> allocator to make sure that they start on cache line boundaries) can
> improve performance by as much as 20%.
> 
The pmap code is a perfect example of that.  There are times that I have
"improved" the code, and noted a net slowdown, because it has grown.
Soon, I intend to chop out another 1-2k out of pmap.o.  Smaller is
definitely better sometimes.

John