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From: news@prg.ox.ac.uk (news)
Newsgroups: comp.sys.acorn
Subject: Re: ARM-3 benchmarks
Message-ID: <1718@culhua.prg.ox.ac.uk>
Date: 13 May 91 14:04:41 GMT
References: <1694@culhua.prg.ox.ac.uk> <10164@castle.ed.ac.uk>
Reply-To: as@prg.ox.ac.uk (Andrew Stevens)
Organization: Oxford University Computing Laboratory, UK
Lines: 45

My mystification at the SUN vs Arch dhrystone ratings (what
would Freud say about this ? :-) ) abates.

Dave Redman got
>       Machine         Dhyrstones per sec
>       ARM2            5289
>       ARM3 @ 25Mhz    14883
>       SUN3/60         2888
>       SUN/Spark1      8000
>       SUN/Spark2      16000

whilst Rik Renwick obtained

>	Machine		Dhrystones/sec	  
>	 Sparc SLC	  10000
>	 Sparc 2	  25000
>	 Sun 3/60	   3333

It turns out these figures are right (mod deviation due to clock
granularity etc) ... for the benchmark run.  However, as run, the
benchmark is more than a little unfair on the SUNs.  This is because the
benchmark (as given to me by Rik) uses the *default* optimisation level
of the compilers.  On the SUNs this is no optimisation at all, on the
Arch this is full optimisation!  If you use comparable optimisations
(CSE, auto register, loop tweaking = default on the Arch, -O2 on SUN) the
figures are (roughly):

SPARCstation-1/SLC = 14500  (a -2 runs around twice as fast)
SUN-3/60	   = 4000   (gcc squeezes out around 4500)

which is in line with published figures.  The fact my 30Mhz ARM3 A410
runs *my* programs a lot slower than SPARCstation-1's is explained by
the style of program: big, heavy register usage and pointer bashing.
SUN's hardware - SPARC register windows and big (but dumb) cache - does
well on the former two points.  SUN's compiler does well on the latter
because it can optimise pointers (and other stuff) in ways that Acorn's
cannot.  The fact that the machine my memories of run-time related to
was a 1+ (25% faster clock) helped a bit too!


        Andrew Stevens                  
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