CODEWITHSUNDEEP
mpiintel
ubc_ben
ubc_ben

Reputation: 163

number of MPI processes can exceed number of logical processors on a node

I have a simple MPI code that print out the rank of process, compiled and linked with Intel compiler and MPI library. Then I ran it on the master node of a cluster interactively: mpiexec -n 50 ./a.out The node only have 12 cores and 24 logical processors (hyperthreading?). But I can ran it with 50 and even more processes. What's the reason?

Upvotes: 2

Views: 1965

Answers (1)

pedromrnd
pedromrnd

Reputation: 153

The processes can run on the same core, the operating system schedule the process, given some amount of CPU time to each one.

In MPI, using more processes than cores is called 'oversubscribing'.For more information see the following URL: http://www.open-mpi.org/faq/?category=running#oversubscribing

Upvotes: 7

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