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Subject: [OMPI users] busy wait in MPI_Recv
From: Brian Budge (brian.budge_at_[hidden])
Date: 2010-10-19 21:43:27

Hi all -

I just ran a small test to find out the overhead of an MPI_Recv call
when no communication is occurring. It seems quite high. I noticed
during my google excursions that openmpi does busy waiting. I also
noticed that the option to -mca mpi_yield_when_idle seems not to help
much (in fact, turning on the yield seems only to slow down the
program). What is the best way to reduce this polling cost during
low-communication invervals? Should I write my own recv loop that
sleeps for short periods? I don't want to go write someone that is
possibly already done much better in the library :)