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From: gillies@m.cs.uiuc.edu
Newsgroups: comp.arch
Subject: Slow SPARC SLC?
Message-ID: <3300201@m.cs.uiuc.edu>
Date: 26 Oct 90 05:58:00 GMT
Lines: 45
Nf-ID: #N:m.cs.uiuc.edu:3300201:000:1564
Nf-From: m.cs.uiuc.edu!gillies    Oct 26 00:58:00 1990


I'm trying to benchmark some code on a SPARC SLC with a color monitor.
Surprisingly, I can only soak up 25% of the CPU.  Has anyone else
encountered this problem?  Is that other 75% of the CPU in the box, or
is it an extra-cost option?  I'm rather disappointed.  The wall-clock
time on the SPARC is much greater than the wall-clock time on our
Multimax, yet the time command is claiming the SPARC has the potential
to be faster.  What am I doing wrong?

What is to stop a vendor from modifying the kernal to lie about how
much CPU is available (oh, our CPU is as fast as a CRAY-5, but
unfortunately the OS takes 99.9% of the CPU.  Just multiply our
CPU-time figures by 1000 to get the actual speed of your benchmark...)

[ on SPARC with no other users ]

% time a.out
Iters   Ticks   Ticks   Ticks   (60ths of a second)
500     1       3       1       
1000    4       5       2      
2000    10      11      6
5000    28      30      17     
10000   61      63      36   
20000   124     128     78     
50000   312     322     209
100000  624     646     428
55.6u 0.3s 3:39 25% 0+720k 0+0io 1pf+0w

[ on Multimax ]

% time a.out
Iters   Ticks   Ticks   Ticks
500     4       5       6 
1000    9       11      11
2000    20      24      24
5000    57      65      67
10000   122     139     148  
20000   251     287     317  
50000   635     747     852  
100000  1286    1473    1751 
143.6u 1.0s 2:24 99% 0+8k 0+0io 0pf+0w

(I presume something is wrong with the multimax page-counting
algorithm, since the program actually takes about 800k on the
multimax).