https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858178#M2191 <P>Thanks for your explanation</P> Wed, 31 Mar 2010 07:56:28 GMT chdthanh 2010-03-31T07:56:28Z https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858176#M2189 <P>Does Intel Core 2 Duo mean 2 processors?<BR />When I use MPI subroutine MPI_COMM_SIZE I got size=1. Does it means that there are 1 processors?Andthe reason is that I useWinXP 32-bit?<BR />Can you please tell how to use 2 processors?<BR />Thanks,<BR />Thanh</P> Tue, 30 Mar 2010 15:30:38 GMT https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858176#M2189 chdthanh 2010-03-30T15:30:38Z https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858177#M2190 No, MPI_COMM_SIZE doesn't tell anything about the number of processors, under either of the common definitions. Core 2 Duo is certainly capable of running 2 MPI ranks, or 2 OpenMP threads, even under XP32. Did you start your job by mpirun -np 2 or similar ?<BR />MPI implementations, in my experience, never pick a number of ranks automatically, unlike OpenMP, where some implementation default to 1 thread, and others default to total number of cores or logicals.<BR />Intel like to call a Core 2 Duo a single processor dual core, even though the term logical processors also is used, particularly for HT. Many MPI users consider dual core as 2 processors. Tue, 30 Mar 2010 21:19:10 GMT https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858177#M2190 TimP 2010-03-30T21:19:10Z https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858178#M2191 <P>Thanks for your explanation</P> Wed, 31 Mar 2010 07:56:28 GMT https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Number-of-processors/m-p/858178#M2191 chdthanh 2010-03-31T07:56:28Z