Dear Jeff, Dear George, Dear Dave, Dear all, so, is it correct to use *MPI_Waitall *? Is my program ok now? Do you see other problems?
Thanks again Diego On 9 January 2015 at 18:39, George Bosilca <bosi...@icl.utk.edu> wrote: > I totally agree with Dave here. Moreover, based on the logic exposed by > Jeff, there is no right solution because if one choose to first wait on the > receive requests this also leads to a deadlock as the send requests might > not be progressed. > > As a side note, posting the receive requests first minimize the potential > for unexpected requests. > > George. > > > On Fri, Jan 9, 2015 at 12:31 PM, Dave Goodell (dgoodell) < > dgood...@cisco.com> wrote: > >> On Jan 9, 2015, at 7:46 AM, Jeff Squyres (jsquyres) <jsquy...@cisco.com> >> wrote: >> >> > Yes, I know examples 3.8/3.9 are blocking examples. >> > >> > But it's morally the same as: >> > >> > MPI_WAITALL(send_requests...) >> > MPI_WAITALL(recv_requests...) >> > >> > Strictly speaking, that can deadlock, too. >> > >> > It reality, it has far less chance of deadlocking than examples 3.8 and >> 3.9 (because you're likely within the general progression engine, and the >> implementation will progress both the send and receive requests while in >> the first WAITALL). >> > >> > But still, it would be valid for an implementation to *only* progress >> the send requests -- and NOT the receive requests -- while in the first >> WAITALL. Which makes it functionally equivalent to examples 3.8/3.9. >> >> That's not true. The implementation is required to make progress on all >> outstanding requests (assuming they can be progressed). The following >> should not deadlock: >> >> ----✂---- >> for (...) MPI_Isend(...) >> for (...) MPI_Irecv(...) >> MPI_Waitall(send_requests...) >> MPI_Waitall(recv_requests...) >> ----✂---- >> >> -Dave >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users >> Link to this post: >> http://www.open-mpi.org/community/lists/users/2015/01/26154.php > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/01/26155.php >
