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Subject: Re: [OMPI users] Behavior of MPI_Send
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-11-15 12:55:19

No. The MPI standard only guarantees that the local buffer is
available for re-use when MPI_SEND returns. It does not guarantee
anything about the receiver or the transmission of the message. If
you need a guarantee about receiver behavior, try MPI_SSEND -- it
won't return until the receiver has posted a matching receive (but
does not guarantee that the receiver has *finished* receiving the

On Nov 15, 2009, at 9:25 AM, Charles Salvia wrote:

> I'm confused about the required behavior of MPI_Send() using TCP
> sockets. Does a call to MPI_Send() block until the receiving
> process actually receives the message, or does MPI_Send() only block
> until the send operation completes locally? In other words, does
> the sender actually have to wait for an ACK from the receiver to
> proceed?
> -Charles Salvia
> _______________________________________________
> users mailing list
> users_at_[hidden]

Jeff Squyres