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From: edhall@randvax.UUCP (Ed Hall)
Newsgroups: net.arch
Subject: Re: Cache revisited
Message-ID: <2659@randvax.UUCP>
Date: Wed, 21-Aug-85 00:31:16 EDT
Article-I.D.: randvax.2659
Posted: Wed Aug 21 00:31:16 1985
Date-Received: Sun, 25-Aug-85 01:35:39 EDT
References: <5374@fortune.UUCP> <901@loral.UUCP> <2583@sun.uucp> <5459@fortune.UUCP>
Reply-To: edhall@rand-unix.UUCP (Ed Hall)
Distribution: net
Organization: Rand Corp., Santa Monica
Lines: 18
Summary: 

Concerning the 68020's cache:

I can think of a lot of places where a loop would fit in a 256-byte
cache, especially in string-processing applications.  Remember, in many
applications a lot of time is spent simply copying memory, making
searches, and so forth.  This isn't just limited to strings: matrix
operations usually include small inner loops where the bulk of computer
time is spent.  The same is true of bit-map graphics.  And it is true
for a lot of other CPU-hungry applications.

So something close to a 50% hit rate wouldn't surprise me for a fairly
large class of programs, though there is probably a larger class of
programs that wouldn't do nearly that good.   If Motorola were claiming
it as an *average* I'd wonder who they thought they were fooling, but
I don't believe they are doing so.

		-Ed Hall
		decvax!randvax!edhall