Messages in this thread | | | Date | Tue, 22 Mar 2005 03:01:01 +0100 | From | Daniel Andersen <> | Subject | Re: Distinguish real vs. virtual CPUs? |
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Dan Maas wrote: > Is there a canonical way for user-space software to determine how many > real CPUs are present in a system (as opposed to HyperThreaded or > otherwise virtual CPUs)? > > We have an application that for performance reasons wants to run one > process per CPU. However, on a HyperThreaded system /proc/cpuinfo > lists two CPUs, and running two processes in this case is the wrong > thing to do. (Hyperthreading ends up degrading our performance, > perhaps due to cache or bus contention). > > Please CC replies. > > Thanks, > Dan Maas > -
The simplest thing to do would be to boot with the "noht" parameter.
Or you can use "schedtool" (google or freshmeat) to set the CPU-affinity at runtime to avoid HyperThreading the processes.
Daniel Andersen
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