Ashley Pittman <ashley <at> pittman.co.uk> writes: > MPI_Comm_split() is an expensive operation, sure the manual says it's low cost but it shouldn't be used > inside any critical loops so be sure you are doing the Comm_Split() at startup and then re-using it as and > when needed. > > Any blocking call into OpenMPI will poll consuming CPU cycles until the call is complete, you can mitigate > against this by telling OpenMPI to aggressively call yield whilst polling which would mean that your > parallel Lapack function could get the CPU resources it required. Have a look at this FAQ entry for details > of the option and what you can expect it to do. > > http://www.open-mpi.org/faq/?category=running#force-aggressive-degraded > > Ashley. >
Thanks for your detailed responses. Actually, the problem came from a stupied error of me... However, I'll have a depth look about the active waiting you describe. I'll try to see if it affects my performances. Jérôme
