Re: [OMPI users] Problems with computation-communication overlap in non-blocking mode

2014-03-11 Thread Velickovic Nikola
11, 2014 3:30 PM To: Open MPI Users Subject: Re: [OMPI users] Problems with computation-communication overlap in non-blocking mode Yes, you're seeing more-or-less the expected behavior. It's a complicated issue. Short version: you might want to sprinkle MPI_Test's

Re: [OMPI users] Problems with computation-communication overlap in non-blocking mode

2014-03-11 Thread Jeff Squyres (jsquyres)
Yes, you're seeing more-or-less the expected behavior. It's a complicated issue. Short version: you might want to sprinkle MPI_Test's throughout your compute stage to get true overlap. More detail: MPI's typically use a "rendezvous" protocol for large messages, meaning that it sends a small f

[OMPI users] Problems with computation-communication overlap in non-blocking mode

2014-03-07 Thread Velickovic Nikola
Dear all, I have a simple MPI program with two processes using non-blocking communication illustrated bellow: process 0: process 1: MPI_Isend MPI_Irecv compute stage compute stage MPI_Wait MPI_Wait Actual communication is performed by offloading it to another thre