Measuring Communication and Computation Overlap
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Measuring Pure Communication Time
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallgather
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallgather_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallgatherv
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallgatherv_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallreduce
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iallreduce_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ialltoall
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ialltoall_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ialltoallv
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ialltoallv_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ibarrier
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ibarrier_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ibcast
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ibcast_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Igather
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Igather_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Igatherv
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Igatherv_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ireduce
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ireduce_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ireduce_scatter
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Ireduce_scatter_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iscatter
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iscatter_pure
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iscatterv
                                                    
                                                    
                                                
                                                    
                                                    
                                                        Iscatterv_pure
                                                    
                                                    
                                                
                                            
                                        IMB-IO Blocking Benchmarks
This section describes blocking I/O benchmarks. The benchmarks can run with varying transfer sizes X, in bytes. The timings are averaged over multiple samples. The basic MPI data type for all data buffers is MPI_BYTE. In the definitions below, a single sample with a fixed I/O size X is used.
Every benchmark contains an elementary I/O action, denoting a pure read or write. Thus, all benchmark flavors have a Write and a Read component. The [ACTION] placeholder denotes a Read or a Write alternatively.
The Write flavors of benchmarks include a file synchronization with different placements for aggregate and non-aggregate modes.
I/O Benchmarks, Aggregation for Output
