> On Thu, 2009-06-04 at 14:54 +1000, Lars Andersson wrote: >> Hi Gus, >> >> Thanks for the suggestion. I've been thinking along those lines, but >> it seems to have drawbacks. Consider the following MPI conversation: >> >> Time NODE 1 NODE 2 >> 0 local work local work >> 1 post n-b recv local work >> 2 local work post n-b send >> 3 complete recv in 1 local work > > Its been awhile since i did mpi programming but... > why not just post a n-b recv for the header too? > just tag it correctly.
I guess that would be a partial cure, but not optimal. The problem is that I can't allocate a buffer of appropriate size and post the main data transfer (MPI_Irecv) call until I have received the size from the header message. So, after posting the recv for the header on NODE 1 and getting on with local work, I would have to call MPI_Test() at regular intervals to check if the header has arrived, and then post a recv for the main transfer. I guess that would work, but if there's a nicer solution, I'd like to find out. /Lars
