[mpich-discuss] MPI how to support the smp machine?

[liaoyin]

I am runing the  HPL ( A Portable Implementation of the High-Performance
Linpack Benchmark for Distributed-Memory Computers) to do linpcke test.

I use the Atlas to as blas lib.

My machine has  one cpu with four core.

I run the mpirun -np 1 ./xhlp   the Gflops is 0.4  (one core to run)

but  I run the mpirun -np 2  ./xhlp the Gflops is 0.04 (two core to run)

why is the two core is slower.
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