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From: Marcin Skoczylas (Marcin.Skoczylas_at_[hidden])
Date: 2006-09-15 06:10:44

Brian Barrett wrote:
> On Jul 5, 2006, at 8:54 AM, Marcin Skoczylas wrote:
>> I saw some posts ago almost the same question as I have, but it didn't
>> give me satisfactional answer.
>> I have setup like this:
>> GUI program on some machine (f.e. laptop)
>> Head listening on tcpip socket for commands from GUI.
>> Workers waiting for commands from Head / processing the data.
>> And now it's problematic. For passing the commands from Head I'm
>> using:
>> while(true)
>> {
>> MPI_Recv...
>> do whatever head said (process small portion of the data, return
>> result to head, wait for another commands)
>> }
>> So in the idle time workers are stuck in MPI_Recv and have 100% CPU
>> usage, even if they are just waiting for the commands from Head.
>> Normally, I would not prefer to have this situation as I sometimes
>> have
>> to share the cluster with others. I would prefer not to stop whole mpi
>> program, but just go into 'idle' mode, and thus make it run again
>> soon.
>> Also I would like to have this aggresive MPI_Recv approach switched on
>> when I'm alone on the cluster. So is it possible somehow to switch
>> this
>> mode on/off during runtime? Thank you in advance!
> Currently, there is not a way to do this. Obviously, there's not
> going to be a way that is portable (ie, compiles with MPICH), but it
> may be possible to add this in the future. It likely won't happen
> for the v1.1 release series, and I can't really speak for releases
> past that at this point. I'll file an enhancement request in our
> internal bug tracker, and add you to the list of people to be
> notified when the ticket is updated.
> Brian

Is there any solution ready? using MPI_Probe before MPI_Recv didn't help
too much.

greetings, Marcin