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HP OpenVMS Systemsask the wizard |
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The Question is: What computational improvement is added with each additional CPU? What special info do I need before converting HP UX to DEC UNIX using DEC C++ compiler to run on Alpha? The Answer is :
> What computational improvement is added with each additional CPU?
This is a very generic question with little or no VMS specifics to it.
The APPLICATION will largely define how effective an additional CPU
will be. If the application is a single large monolithic (cobol)
program then adding a CPU will offer no, or minimal, help.
If the application consists of many, completely independend, largely CPU
bound jobs then each CPU added will bring almost 100% more processnig
power to that application.
As most applications have some interdependencies between activity, the
real added value is mostly expressed as a factor.
Adding CPU N is then believed to add that factor to the power of N-1.
For example, if that factor is 0.9, the power for a 1,2,3 Cpu
configurations will be 1.0, 1.9 (1 + .9), 2.71 (1 + .9 + .81),...
Typical factors are in the 0.8 (bad) to 0.95 (range).
This means that adding CPUs beyond about 8 or so tends NOT to help
too much more.
What special info do I need before converting HP UX to DEC UNIX using DEC C++ compiler to run on Alpha?
This is a VMS Wizard. Ask a Unix Wizard?
hth
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