nather@utastro.UUCP (Ed Nather) (12/21/84)
[--+- begone!]
The December 1984 issue of Byte magazine lists a benchmark test in C
that is computationally intensive using long integer arithmetic. The
process involves factoring a very large number by an iterative method.
The author, David C. Clark, lists execution times for the program on a
Z80 computer with a 4MHz clock, for two different compilers, Aztec C and
Eco-C. I compiled and ran the same program on an IBM PC (4.77 MHz
clock, 8088 chip) using the DeSmet C compiler and the optimizing CI-C86
compiler. I also ran the same program on a Vax 11/780 running 4.2BSD
Unix. Here are the execution times:
Compiler Computer Execution time (min:sec.)
Aztec Z80 2:06
Eco-C Z80 1:41
CI-C86 IBM-PC 0:22.4
DeSmet C IBM-PC 0:10.1
PCC Vax 11/780 0:00.4
Apparent conclusions:
1. 32-bit machines handle 32 bit integers faster than 16 bit machines,
and 16 bit machines handle them faster than 8 bit machines, by about
an order of magnitude or better in each case.
2. Some compilers generate faster code than others for the same machine,
by perhaps a factor of 2 or so. The "optimizing" compiler is not
always the faster.
3. Benchmarks aren't the whole story, but I seriously doubt that anyone
could devise one that would reverse the ordering of execution times
for the above three computers.
4. As a rough figure of merit (for this type of operation only) we can
multiply the time by the cost of the computer. Averaging the times
where there are more than one, and taking the approximate cost of the
computers involved, I get that the Vax and the IBM PC have about the
same figure of merit, while the Z80 system is about 3 times worse.
Curious. Anybody want to try it on their Macintosh?
Ed Nather
Astronomy Dept., U of Texassjl@amdahl.UUCP (Steve Langdon) (12/23/84)
I ran the test on my Macintosh using Mac C (TM) from Consulair Corp.
The execution time was 2.75 seconds. For those who are also interested in
compile time, the results were:
compile 15 seconds
assemble 11 seconds
link 44 seconds
These times were obtained using my normal operating procedure, which involves
running with a RAM disk containing a small copy of the system, Fast Finder (TM),
Exec, C, Assembler, and Linker. The source files, libraries etc. are on one
floppy and EDIT, RMaker, etc. are on the other floppy. I used an Exec job file
to compile and link. Timing was started when I pressed the execute button in
Exec. Thus the times above include application startup and so on. The complete
elapsed time from starting the compile to having an executable version of the
program was 70 seconds.
While I was at it I decided I might as well make other people jealous by running
the test on the UTS system I use at work (running under VM on an Amdahl 470/V8).
The results were:
execute UTS % timex -p a.out
Factoring...
A factor of 1394761 is 1181
It took 871 iterations
real 0.20
user 0.03
sys 0.01
compile UTS % timex -p cc factor.c
real 2.63
user 0.33
sys 0.36
The results reported before were:
Compiler Computer Execution time (min:sec.)
Aztec Z80 2:06
Eco-C Z80 1:41
CI-C86 IBM-PC 0:22.4
DeSmet C IBM-PC 0:10.1
PCC Vax 11/780 0:00.4
I think both the Macintosh and the V8 look pretty good on this test.
--
Stephen J. Langdon ...!{ihnp4,hplabs,sun,nsc}!amdahl!sjl
[ The article above is not an official statement from any organization
in the known universe. ]