SUMMARY: Performance of a single job in a multi-CPU environment

From: Zina Yung (
Date: Thu Mar 13 1997 - 01:39:05 CST

Hello SUN managers:

My original posting:

  Can one get any speed gain from the dual-CPU config on a single
  *ordinary* job? I.e., assuming no attempt has been made by a
  programmer to write a parallel program, and you run just one single
  job, does the system automatically do any low-level parallelizing
  to speed up your single job? If so, what kind of speed gain could
  one reasonably hope to get? (I realize that any speed gain would
  be highly dependent on the nature of the job, but just want a rough

My summary:
Thanks for all those replied! The majority said there is NO gain
        . you use parallelizing compiler such as SUN's Impact.
        . use some parallel virtual machine (e.g. PVM). This will
          allow your source to be modified to treat each processor as
          a distributed node.
        . the program does some forking, or spawning of other jobs.

Many thanks to:
       Bert N. Shure
       Michael R. Zika
       Matthew Stier
       Rich Kulawiec
       Kai O'Yang
       James H. McG. Sibl
       Greg Price
       Peter Bestel
       Kevin Sheehan
       Alex Finkel
       Marc S. Gibian
       Jay Lessert

Details of the responses:

From: "Bert Shure" <>

no luck unless the application is written to take advantage of multiple

the only winning aspect of the two processor system is that one
processor could use all the memory if nothing else is happening on the

From: "Michael R. Zika" <>

If you're looking at a parallel applications, I would recommend one of
the following:

   o Purchase the iMPact toolkit with the SunSoft compilers. This will
     let you code shared-memory parallel directives into your code.
     I've used these and had good success with some small real world
     applications. It also provides and auto parallelization option.

   o Install PVM (Parallel Virtual Machine) or MPI (Message Passing
     Interface). This will allow your source to be modified to treat
     each processor as a distributed node. This allows you to treat
     your shared memory machine as a distributed memory machine (if
     that's what you want)

In both cases, source code modifications will be required.
From: "Matthew Stier" <>

1) There never is just 'one' job running on a computer.

2) If the program does any forking, or spawning of other jobs, you can expect
some improvement.

3) You don't necessarily need multi-threading, to get a performance boost from
a multi-processor computer.

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From: "Scott Williamson" <>
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Organization: Morse Computers
Date: Thu, 13 Mar 1997 09:23:50 +0000
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Subject: SUMMARY: Boot Prom version
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Thanks to all who wrote.

"prtconf -V" shows Open Boot Prom revision, which is not quite what
I wanted. Got a value of "OBP 3.1.1 1996/03/08 14:20" on my system.

Stop-A on the console, followed by "banner" then "go" to resume gives
the ROM revision, 2.28, which is what I was really after. Maybe I
didn't ask the correct question.

This is the value which, for example, has to be at least 2.25 to be
able to use Ross HyperSPARC modules in a SPARC 20.

Other people mentioned the "sysinfo" package as something which might
give this information. It would be nice to think that there's some
way of getting it without hanging the system.


Scott Williamson Morse Computers Tel.: 0131 226 3300 Senior Consultant 60 Melville Street Direct: 0131 260 3314 Edinburgh Fax: 0131 226 3535 EH3 7HF Mobile: 0370 865370

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