Subject: Re: Large CPU caches & NetBSD
To: Jon Lindgren <jlindgren@espus.com>
From: Brett Lymn <blymn@baea.com.au>
List: netbsd-help
Date: 04/06/2000 19:54:40
According to Jon Lindgren:
>
>Will a large CPU cache result in a noticable (I don't expect build times
>to cut in half, but I'd expect a _small_ change) change in NetBSD's
>performance?
>

Depending on how much cache you had before will determine how much of
a change you see.  Going from no cache to a little cache can make a
very big difference but the effect tails off after a while, which you
probably knew already :-)

>  I've managed to get my hands on some PPro 200MHz 1mb cpus,
>and I was just thinking about things like how often the cache is flushed,
>how other things might affect the cache usage.

From what I have read there should be little need to flush a pentium
cache, the hardware pretty much manages itself.

>  Even better, does anyone
>have any good references where I can read about this (perhaps specifically
>relating to NetBSD)?
>

For more than you ever wanted to know about caches, their coherency
and how they work in a SMP system, check out "Unix Systems for Modern
Architectures, Symmetric Multiprocessing and Caching for Kernel
Programmers" by Curt Schimmel (ISBN 0-201-63338-8) from Addison Wesley.

-- 
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Brett Lymn, Computer Systems Administrator, BAE SYSTEMS
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