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Subject: Re: [OMPI users] Receiving MPI messages of unknown size
From: Neil Ludban (nludban_at_[hidden])
Date: 2009-06-04 10:27:50


> Date: Thu, 4 Jun 2009 11:14:16 +1000
> From: Lars Andersson <larsand_at_[hidden]>
> Subject: [OMPI users] Receiving MPI messages of unknown size
> To: users_at_[hidden]
>
> When using blocking message passing, I have simply solved the problem
> by first sending a small, fixed size header containing the size of
> rest of the data, sent in the following mpi message. When using
> non-blocking message passing, this doesn't seem to be such a good
> idea, since we cant post the main data transfer until we have received
> the message header... It seems to take away most of the advantages on
> non-blocking io in the first place.

If enough messages are small enough, a medium sized message with
fixed header and variable data eliminates most of the second message
overhead.