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mattsdad
Beginner
47 Views

Hyperthreading in dual-dual processor

I am running an extreemly CPU intensive multi-body simulation which lend itself nicely to parallel processing. We have run several tests with the same simulation using a single-threaded compilation and a multi-threaded compilation. We have run the same simulation with the hyper-threading on and off. Here are the results:

The 12-body simulation on the dual-dual core Xeon machine runs about 70% faster when using the multi-threaded compilation compared to the single-threaded compilarion.

When we turn hyper-threading on, the execution of the multi-threaded compilation slows down about 15%. In this CPU intensive simulation, the 8 processor threads fight for CPU time and only average about 50% CPU time for each hyper-thread. With the hyper-threading off, the same simulation uses all four CPUs at almost 100% throughout the simulation.

So, we are are turning hyper-threading off because most of our processor time is spent running these CPU intensive simulations.

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2 Replies
TimP
Black Belt
47 Views

Memory contention seems a more likely reason for low CPU utilization with increased number of threads. Several factors could be involved, including which OS you use.

mattsdad
Beginner
47 Views

There is no question or problem here. I was only providing the data so others could use this data point in their evaluations. Maybe encourage checking the speed with and without hyper-threading for their own programs.
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