2.6.1 Deprecated and Removed Interfaces 2.6.9 Fortran Binding Issues. 2.6.3 C Binding Iss 26.4 tions and Mac 2.7 28 Error Handling 2.0 2.9.1 of Basic Runtime 2.9.2 with Si 2.10 gnals Examples. 3 Point-to-Point Communication 31 3.1 Introduction 3.2 Blocking Send and Receive Operations 3.21 Blocking Send 322 Message Data 3.2.3 Message envelope 324 Blocking Receive 325 Return Status 3.2.6 Passing MPI_STATUS_IGNORE for Status 327 Blocking Send Receive 42 3.3 Datatype Matching and Data Conversion 3.3.1 Type Matchi ng rules Type MPI_CHARACTER 3.3.2 Data Conv sion 3.4 Co mication modes 3.5 Semantics of Point-to-Point Communication 3.6 Buffer Allocation and Usage 947 3.6.1 Model Implementation of Buffered Mod 3.7 Nonblocking Co 271 Co nication re Obi 379 3.7.3 37 tics of Nonblocking C nicati 3.75 Multiple Co 3.7.6 Dest ctive Tes 3.8 and Cancel 3.82 D 3.8.3 ched Receives 38 7188880090 3.9 ent on Null Processes Requests 3.10 4 Partitioned Point-to-Point Communication 103 4.1 Introduction 103 4.2 Semantics of Partitioned point-to-Point communication 104 421 Communication Initialization and Starting with Partitioning 1062.6.1 Deprecated and Removed Interfaces . . . . . . . . . . . . . . . . . 23 2.6.2 Fortran Binding Issues . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.6.3 C Binding Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.6.4 Functions and Macros . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.7 Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.8 Error Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.9 Implementation Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.9.1 Independence of Basic Runtime Routines . . . . . . . . . . . . . . 28 2.9.2 Interaction with Signals . . . . . . . . . . . . . . . . . . . . . . . . 29 2.10 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3 Point-to-Point Communication 31 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.2 Blocking Send and Receive Operations . . . . . . . . . . . . . . . . . . . . 32 3.2.1 Blocking Send . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2.2 Message Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2.3 Message Envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.4 Blocking Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.2.5 Return Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.2.6 Passing MPI_STATUS_IGNORE for Status . . . . . . . . . . . . . . . 41 3.2.7 Blocking Send-Receive . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.3 Datatype Matching and Data Conversion . . . . . . . . . . . . . . . . . . . 45 3.3.1 Type Matching Rules . . . . . . . . . . . . . . . . . . . . . . . . . 45 Type MPI_CHARACTER . . . . . . . . . . . . . . . . . . . . . . . . 47 3.3.2 Data Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3.4 Communication Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.5 Semantics of Point-to-Point Communication . . . . . . . . . . . . . . . . . 54 3.6 Buffer Allocation and Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.6.1 Model Implementation of Buffered Mode . . . . . . . . . . . . . . 60 3.7 Nonblocking Communication . . . . . . . . . . . . . . . . . . . . . . . . . . 60 3.7.1 Communication Request Objects . . . . . . . . . . . . . . . . . . . 62 3.7.2 Communication Initiation . . . . . . . . . . . . . . . . . . . . . . . 62 3.7.3 Communication Completion . . . . . . . . . . . . . . . . . . . . . . 70 3.7.4 Semantics of Nonblocking Communications . . . . . . . . . . . . . 74 3.7.5 Multiple Completions . . . . . . . . . . . . . . . . . . . . . . . . . 75 3.7.6 Non-Destructive Test of status . . . . . . . . . . . . . . . . . . . . 83 3.8 Probe and Cancel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.8.1 Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.8.2 Matching Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 3.8.3 Matched Receives . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.8.4 Cancel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 3.9 Persistent Communication Requests . . . . . . . . . . . . . . . . . . . . . . 94 3.10 Null Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4 Partitioned Point-to-Point Communication 103 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 4.2 Semantics of Partitioned Point-to-Point Communication . . . . . . . . . . 104 4.2.1 Communication Initialization and Starting with Partitioning . . . 106 vi