https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Co-Array-vs-OpenMP-using-Intel-ifort-v12-Process-based-Co-Array/m-p/769585#M110 I am testing co-array using /Qcoarray:shared on my core 2 duo PC. It looks like Intel's co-array is just a wrapper to mpiexec. <BR /><BR />For example, if I run a co-array application, there will be 3 processes launched, presumably, one master controlling process, and 2 worker processes. From what I can tell, the co-array are not using multi-thread, but rather, process based. If I do a ctrl-C in the middle of the run, it aborts 2 process, and a message saying mpiexec abort is done. <BR /><BR />So, am I right that Intel's co-array (with /Qcoarray:shared) is process based MPI wrapper?<BR /><BR />---------------------------<BR /><BR />Basically on above observation, I expect the co-array code will be much slower than the multi-threading based OpenMP code.<BR /><BR />I actually tested some small codes in "A Comparison of Co-Array Fortran and OpenMP<BR />Fortran for SPMD Programming" (http://www7300.nrlssc.navy.mil/global_nlom/globalnlom/pubs-data/wallcraft-2002.pdf). In deed, the co-array version of the calculating PI is about 30-40% slower than the OpenMP version. <BR /><BR />A stunning and disappointing finding.<BR /><BR /><BR /> Mon, 04 Apr 2011 22:01:18 GMT a_zhaogtisoft_com 2011-04-04T22:01:18Z https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Co-Array-vs-OpenMP-using-Intel-ifort-v12-Process-based-Co-Array/m-p/769585#M110 I am testing co-array using /Qcoarray:shared on my core 2 duo PC. It looks like Intel's co-array is just a wrapper to mpiexec. <BR /><BR />For example, if I run a co-array application, there will be 3 processes launched, presumably, one master controlling process, and 2 worker processes. From what I can tell, the co-array are not using multi-thread, but rather, process based. If I do a ctrl-C in the middle of the run, it aborts 2 process, and a message saying mpiexec abort is done. <BR /><BR />So, am I right that Intel's co-array (with /Qcoarray:shared) is process based MPI wrapper?<BR /><BR />---------------------------<BR /><BR />Basically on above observation, I expect the co-array code will be much slower than the multi-threading based OpenMP code.<BR /><BR />I actually tested some small codes in "A Comparison of Co-Array Fortran and OpenMP<BR />Fortran for SPMD Programming" (http://www7300.nrlssc.navy.mil/global_nlom/globalnlom/pubs-data/wallcraft-2002.pdf). In deed, the co-array version of the calculating PI is about 30-40% slower than the OpenMP version. <BR /><BR />A stunning and disappointing finding.<BR /><BR /><BR /> Mon, 04 Apr 2011 22:01:18 GMT https://community.intel.com/t5/Intel-Moderncode-for-Parallel/Co-Array-vs-OpenMP-using-Intel-ifort-v12-Process-based-Co-Array/m-p/769585#M110 a_zhaogtisoft_com 2011-04-04T22:01:18Z