Code review: What happens in Open-MPI's MPI_Iprobe ? Update 1 Subject: Re: [OMPI devel] Implementation of MPI_Iprobe From: George Bosilca (bosilca_at_[hidden]) Date: 2011-09-27 15:34:05 Sebastien, Your analysis is correct in case the checkpoint/restart approach maintained by ORNL is enabled. This is not the code path of the "normal" MPI processes, where the PML OB1 is used. In this generic case the function mca_pml_ob1_iprobe, defined in the file ompi/mca/pml/ob1/pml_ob1_iprobe.c is used. george. http://www.open-mpi.org/community/lists/devel/2011/09/9766.php End of update 1 The message-passing interface (MPI) standard defines an interface for passing messages between processes. These processes are not necessarily running on the same physical computer. Open-MPI is an implementation of the MPI standard. Here, I have utilised openmpi-1.4.3 to find out what is happening when a call to MPI_Iprobe occurs. According to the MPI 2.2 standard "