I personally find the entire MPI one-sided chapter to be incredibly confusing and subject to arbitrary interpretation. I have consistently advised people to not use it since the late '90s.
That being said, the MPI one-sided chapter is being overhauled in the MPI-3 forum; the standardization process for that chapter is getting pretty close to consensus. The new chapter is promised to be much better. My $0.02 is that you might be better severed staying away from the MPI-2 one-sided stuff because of exactly the surprises and limitations that you've run in to, and wait for MPI-3 implementations for real one-sided support. On Feb 24, 2011, at 8:21 AM, Toon Knapen wrote: > But that is what surprises me. Indeed the scenario I described can be > implemented using two-sided communication, but it seems not to be possible > when using one sided communication. > > Additionally the MPI 2.2. standard describes on page 356 the matching rules > for post and start, complete and wait and there it says : > "MPI_WIN_COMPLETE(win) initiate a nonblocking send with tag tag1 to each > process in the group of the preceding start call. No need to wait for the > completion of these sends." > The wording 'nonblocking send' startles me somehow !? > > toon > > > On Thu, Feb 24, 2011 at 2:05 PM, James Dinan <di...@mcs.anl.gov> wrote: > Hi Toon, > > Can you use non-blocking send/recv? It sounds like this will give you the > completion semantics you want. > > Best, > ~Jim. > > > On 2/24/11 6:07 AM, Toon Knapen wrote: > In that case, I have a small question concerning design: > Suppose task-based parallellism where one node (master) distributes > work/tasks to 2 other nodes (slaves) by means of an MPI_Put. The master > allocates 2 buffers locally in which it will store all necessary data > that is needed by the slave to perform the task. So I do an MPI_Put on > each of my 2 buffers to send each buffer to a specific slave. Now I need > to know when I can reuse one of my buffers to already store the next > task (that I will MPI_Put later on). The only way to know this is call > MPI_Complete. But since this is blocking and if this buffer is not ready > to be reused yet, I can neither verify if the other buffer is already > available to me again (in the same thread). > I would very much appreciate input on how to solve such issue ! > thanks in advance, > toon > On Tue, Feb 22, 2011 at 7:21 PM, Barrett, Brian W <bwba...@sandia.gov > <mailto:bwba...@sandia.gov>> wrote: > > On Feb 18, 2011, at 8:59 AM, Toon Knapen wrote: > > > (Probably this issue has been discussed at length before but > unfortunately I did not find any threads (on this site or anywhere > else) on this topic, if you are able to provide me with links to > earlier discussions on this topic, please do not hesitate) > > > > Is there an alternative to MPI_Win_complete that does not > 'enforce completion of preceding RMS calls at the origin' (as said > on pag 353 of the mpi-2.2 standard) ? > > > > I would like to know if I can reuse the buffer I gave to MPI_Put > but without blocking on it, if the MPI lib is still using it, I want > to be able to continue (and use another buffer). > > > There is not. MPI_Win_complete is the only way to finish a > MPI_Win_start epoch, and is always blocking until local completion > of all messages started during the epoch. > > Brian > > -- > Brian W. Barrett > Dept. 1423: Scalable System Software > Sandia National Laboratories > > > > _______________________________________________ > users mailing list > us...@open-mpi.org <mailto:us...@open-mpi.org> > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
