Re: Dual processor How To's ?Different question
- From: David Schwartz <davids@xxxxxxxxxxxxx>
- Date: Tue, 07 Aug 2007 12:43:33 -0700
On Aug 7, 9:15 am, sandy <tks.ku...@xxxxxxxxx> wrote:
Hi David,
Thanks for the quick reply. I will try the same.
But i have a question. I keep hearing statements
something like this..."We are not making use of dual processor , we
are just running same code (written on single processor) on dual
processor.
Not knowing what your code does, it's hard for me to know what to make
of that comment. It might be dead on, it might be complete nonsense.
If we have to make use of Dual Proc we need modify the code
for the same and run. Just increasing the hardware capacity will not
solve the problem.(problem is with single processor the app is able to
serve 3000 requests, but running the same code on dual its able to
serve 7000 requests)." For obvious reasons i am not able to give you
complete information on the problem but its similar.
Can you please provide me your understanding of this above
said stmt?
Not all tasks are CPU limited. Most CPU limited tasks can be
accelerated by a dual processor. If your task is CPU limited, you
should see a significant performance boost on a dual CPU system
compared to a comparable single CPU system.
If your task is limited by disk I/O, network I/O, or memory bandwidth,
another CPU is not likely to help.
If you use multiple processes or multiple threads, the additional CPU
should speed things up without you having to do anything special. But
there are ways that can go wrong (false sharing, too much work has to
be done in one thread, poorly scoped locks, and so on).
The only way to fix a performance problem that only shows up on some
platforms is to analyze performance on one of those platforms.
If one CPU is at 100% and the other is idle, that's a good sign of a
problem. If both CPUs are at 100%, but performance is the same as if
you only allow one CPU to be used, that's a good sign of a problem.
DS
.
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