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

[Zain elabedin hammade]

Hi.
I think you have a bit confusion here ..!
-np $Nprocess  
Nprocess means number of processes that work in parallel ,not the number of cores ...!
In Addition ..MPI works sequentially  on one machine so the load will increase ...

Zain Elabedin   

Date: Fri, 4 Dec 2009 17:02:28 +0800
From: ustcliao at gmail.com
To: mpich-discuss at mcs.anl.gov
Subject: [mpich-discuss] MPI how to support the smp machine?

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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