Thanks for your replay...
Let me be a little insistent... :P
I read (I don't remember where...) that an specific implementation
could send messages with synchronous comm mode... eagerly!
I think it still conform to the standard if the operation completes
just after the ack from the receiver.
The MPI_Ssend() could send a short message eagerly and wait for the
ack... (to satisfy the semantics of synchronous send)
Well, if it's possible.... I want to know if the OPENMPI
implementation (with BTL TCP over Ethernet) uses different protocols
for short/long when synchronous ...
(or it will be always rendezvous... as stated before)
Thanks
Marcelo
On 8/29/06, George Bosilca <bosi...@cs.utk.edu> wrote:
On Tue, 29 Aug 2006, Marcelo Stival wrote:
> Hi,
>
> I have 2 questions related to short/long message protocols...
>
> 1) When using synchronous comm mode, short messages (<64kB) still be
> transferred eagerly?
Depend. 64Kb is not the limits between the eager and rendez-vous protocol.
In fact it depend on the underlying network that get activated. Anyway,
for this particular question this limit between the eager and rendez-vous
protocol does not matter. Synchronous is alway a rendez-vous protocol as
specified in the MPI standard.
> And larger messages will be transferred using rendezvous...?
That's always the case even for non synchronous operations.
>
> 2) When the progress-thread (tcp btl) will be applied?
> Just for long messages? Does it affect synchronous short messages sends?
The behavior will be the same with or without threads.
Thanks,
george.
"We must accept finite disappointment, but we must never lose infinite
hope."
Martin Luther King
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