From: "Alain Coetmeur" <alain.coetmeur@icdc.caissedesdepots.fr>
Newsgroups: comp.parallel.mpi
Subject: WMPI (p4 transport) process consume CPU when waiting ... how to
    wait passively?
Date: Thu, 10 Dec 1998 14:16:54 +0100
Organization: Informatique-CDC
Message-Id: <74ohp1$g5n2@puligny.idt.cdc.fr>
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I'm using WMPI on a network of NT station.
I've programmed a master/slaves model
where a master process send request to slaves
and gather results. all works functionnally.

since the master does nothing else sending and gathering requests
when slaves are ready, I've put it on the same processor/machine as
one of the slave.
but in fact, yet it does nothing, it consume 50% CPU on this machine.
I think that, for performance, synchronization is made via active polling
and not passive wait.

how to configure WMPI (based on MPI-CH) , or maybe p4
so that it does only passive waits.

I've use the -p4noshared option so that processes don't communicat through
shared memory, thinking that active polling was done only for
shared memory IPC. anyway nothing changes.

the MPI primitive that is responsible of the main waste is:
MPI_Waitany().

don't esitate to tell me what is done on unix with MPI-CH or p4 also,
since I can try to transpose it to WMPI/p4 on NT...