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Re: pthreads don't scale on windows xp, but does scale on linux, cygwin 1.5.19


Hi,

jdeifik wrote:
At 07:00 PM 3/21/2006, you wrote:

jdeifik wrote:
I have a dual xeon 2.4ghz machine with hypertreading enabled.
This gives me 4 logical processors.

I am not sure why it is important to have a HT aware scheduler for Windows, when there are 4 or more
threads. I can see with 2 threads you would like to have one per physical processor.
With 4 or more threads, cygwin phtreads really sucks, 4->62%, 6->39%, 8->30% efficiency.

I do not wonder. HT does not give a full CPU to the other thread. If the scheduler is not aware of the problem, it actually slows down the performance of the real CPU.

It seems to me that more and more apps are turning to threading for performance,
and more and more hardware is available with multi-processor, multi-core, and multi-threading.

Yes, this is why programs must be written to run with real CPUs and not something Intel calls HyperThreading.


Erich

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