Seems obvious that Waitany spins on the array of requests until one completes. Is that an active loop by your definition? Jeff On Thursday, July 30, 2015, Dorier, Matthieu <[email protected]> wrote:

Hi,

I have a code that looks like this:

while(true) { do some I/O (HDF5 POSIX output to a remote, parallel file system) wait for communication (MPI_Waitany) from other processes (in the same node and outside the node) }

I'm measuring the energy consumption of the node that runs this process for the same duration, as a function of the amount of data written in each I/O operation. Surprisingly, the larger the I/O in proposition to the communication, the lower the energy consumption. In other words, the longer I wait in MPI_Waitany, the more I consume.

Does anyone have a good explanation for that? Is there an active loop in MPI_Waitany? Another reason?

Thanks!

Matthieu

-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss