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From: preston@ariel.rice.edu (Preston Briggs)
Newsgroups: comp.arch
Subject: Re: More Snake bytes. (X/MHz)
Message-ID: <1991Apr6.012811.6888@rice.edu>
Date: 6 Apr 91 01:28:11 GMT
References: <12914@goofy.Apple.COM> <1991Apr5.213636.18363@leland.Stanford.EDU> <11191@exodus.Eng.Sun.COM>
Sender: news@rice.edu (News)
Organization: Rice University, Houston
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ram@shukra.Eng.Sun.COM (Renu Raman) writes:
>Does anybody know (exactly how) HP was able to improve matrix-300's 
>spec-ratio from 30-odd to 200+  - Just curious....

Well, matrix-300 is normally a cache buster.
With their rather large D-cache, it shouldn't be
nearly as severe, though the problem is still larger than
the cache used for the tests (more than 2Meg vs 128 or 256K).

The multiply-accumulate instruction surely helps too.

Also, it's possible to get a factor of 2 to 3 (or more?)
by inlining and reworking the loops extensively.
If their compilers can do this, there will be many happy customers.

Preston Briggs