Hi,
I have a program where each MPI rank hosts a set of data blocks. After
doing computation over *some of* its local data blocks, each MPI rank needs
to exchange data with other ranks. Note that the computation may involve
only a subset of the data blocks on a MPI rank. The data exchange is
achie
Maybe start the data exchange by sending a (presumably short)
list/array/index-function of the dirty/not-dirty blocks status
(say, 0=not-dirty,1=dirty),
then putting if conditionals before the Isend/Irecv so that only
dirty blocks are exchanged?
I hope this helps,
Gus Correa
On 05/01/2013 01:2
Hi Gus,
Thanks for your suggestion!
The problem of this two-phased data exchange is as follows. Each rank can
have data blocks that will be exchanged to potentially all other ranks. So
if a rank needs to tell all the other ranks about which blocks to receive,
it would require an all-to-all collec
Hi Thomas/Jacky
Maybe using MPI_Probe (and maybe also MPI_Cancel)
to probe the message size,
and receive only those with size>0?
Anyway, I'm just code-guessing.
I hope it helps,
Gus Correa
On 05/01/2013 05:14 PM, Thomas Watson wrote:
Hi Gus,
Thanks for your suggestion!
The problem of this tw
Hi Jacky,
1. If you do not post a matching send, the wait(all) on the recv will stall
forever.
2. You can match a recv(count, tag, src) with a send(0, tag, dst). The recv
will complete, the status can be inspected to verify how many bytes have
actually been received. It is illegal to send mor
Hi Aurelien,
Excellent! Point 2) is exactly what I need - no data is actually sent and
Irecv completes normally.
Thanks!
Jacky
On Wed, May 1, 2013 at 6:29 PM, Aurélien Bouteiller wrote:
> Hi Jacky,
>
> 1. If you do not post a matching send, the wait(all) on the recv will
> stall forever.
> 2.
