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From: mccoy@pixar.uucp (Dan McCoy)
Newsgroups: comp.sys.sgi
Subject: Re: Where's the SPARK in my SPARC????
Message-ID: <1991Feb26.202910.27944@pixar.uucp>
Date: 26 Feb 91 20:29:10 GMT
References: <1991Feb21.120049.5626@jarvis.csri.toronto.edu>
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In article <1991Feb21.120049.5626@jarvis.csri.toronto.edu> corkum@csri.toronto.edu (Brent Thomas Corkum) writes:
>So I compiled the program and ran it, and
>did I get a surprise, it ran 6.5 times slower than the 4D/25. I thought the
>SPARC2 was suppose to be 2-3 times faster in FLOPS.

Aside from the register windows that others mentioned, another
place that SPARC often loses ground versus MIPS processors (like SGI)
is integer multiplies.  Unless they snuck them into the SparcStation 2
when I wasn't looking, SPARC still does multiply in software whereas
MIPS processors have hardware for that.

Even if you think your code is floating point bound, there could be a lot
of integer multiplies that start dominating the run time.
On the SGI using "pixie" you can find out how many integer mulitplies
you are doing.

Dan McCoy	...!{ucbvax,sun}!pixar!mccoy


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