[mvapich-discuss] truly one-sided communication

[Thiago]

Ah pity! I need this for a paper due in a few days.  Hmm, all I really 
need is an RMA read from the target memory which is read-only and never 
modified. I take it this means that synchronization is unneeded? Aside 
from waiting for MPI-3 to hopefully have this as an option (please!), 
how painful would it be to hack MVAPICH2 to simply throw out the 
synchronization so that when I call MPI_Get it only does a single RMA 
read over Infiniband and the lock/unlock skip the communication?  If 
that's too complicated, what would be the next best option?  I have 64 
nodes, each running 8 threads where each thread does computation and 
random MPI_Get communication.  Is there something, (perhaps unportable 
and only works on 1.6-rc2!) that I could do that would let me call 
MPI_Get without having to have the target know this is happening?  
Perhaps using MPI_MODE_NOCHECK and doing "undefined" behavior that 
actually ends up working just this time?  If I must do a standard 
passive communication, what's the best way to ensure my performance 
doesn't tank?  Is there a cheap MPI function I can have a thread do in a 
while loop to ensure that progress is made?

Thanks,
Thiago


On 1/19/2011 7:22 AM, sreeram potluri wrote:
> Dear Thiago,
>
> Thanks for your email. Currently, MVAPICH2 supports truly one-sided 
> communication for the active modes of synchronization (Fence and 
> Post-Wait/Start-Complete) available in MPI-2 RMA. The truly one-sided 
> designs for passive mode are in the pipeline for the next (1.7) 
> release of MVAPICH2.
>
> Thank you
> Sreeram Potluri
>