MPI A MessagePassing Interface Standard Message Passing Interface Forum May This work was supp orted in part by ARPA and NSF under grant ASC the National Science Foundation Science and Technology Center Co op erative Agreement No CCR and by the Commission of the Europ ean Community through Esprit pro ject PPPPE The Message Passing Interface Forum MPIF with participation from over or 1 ganizations has b een meeting since Novemb er to discuss and dene a set of library 2 interface standards for message passing MPIF is not sanctioned or supp orted by any ocial 3 standards organization 4 The goal of the Message Passing Interface simply stated is to develop a widely used 5 standard for writing messagepassing programs As such the interface should establish a 6 practical p ortable ecient and exible standard for message passing 7 This is the nal rep ort Version of the Message Passing Interface Forum This 8 do cument contains all the technical features prop osed for the interface This copy of the 9 a draft was pro cessed by L T X on May 10 E Please send comments on MPI to mpicommentscsutkedu Your comment will b e 11 forwarded to MPIF committee memb ers who will attempt to resp ond 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 c University of Tennessee Knoxville Tennessee Permission to copy with 35 out fee all or part of this material is granted provided the University of Tennessee copyright 36 notice and the title of this do cument app ear and notice is given that copying is by p ermis 37 sion of the University of Tennessee 38 39 40 41 42 43 44 45 46 47 48 1 2 3 4 5 6 Contents 7 8 9 10 11 Acknowledgments vi 12 13 Intro duction to MPI 14 Overview and Goals 15 Who Should Use This Standard 16 What Platforms Are Targets For Implementation 17 What Is Included In The Standard 18 What Is Not Included In The Standard 19 Organization of this Do cument 20 21 MPI Terms and Conventions 22 Do cument Notation 23 Pro cedure Sp ecication 24 Semantic Terms 25 Data Typ es 26 Opaque ob jects 27 Array arguments 28 State 29 Named constants 30 Choice 31 Addresses 32 Language Binding 33 Fortran Binding Issues 34 C Binding Issues 35 Pro cesses 36 Error Handling 37 Implementation issues 38 Indep endence of Basic Runtime Routines 39 Interaction with signals in POSIX 40 41 PointtoPoint Communication 42 Intro duction 43 Blo cking Send and Receive Op erations 44 Blo cking send 45 Message data 46 Message envelop e 47 Blo cking receive 48 Return status Data typ e matching and data conversion 1 Typ e matching rules 2 Data conversion 3 Communication Mo des 4 Semantics of p ointtop oint communication 5 Buer allo cation and usage 6 Mo del implementation of buered mo de 7 Nonblo cking communication 8 Communication Ob jects 9 Communication initiation 10 Communication Completion 11 Semantics of Nonblo cking Communications 12 Multiple Completions 13 Prob e and Cancel 14 Persistent communication requests 15 Sendreceive 16 Null pro cesses 17 Derived datatyp es 18 Datatyp e constructors 19 Address and extent functions 20 Lowerb ound and upp erb ound markers 21 Commit and free 22 Use of general datatyp es in communication 23 Correct use of addresses 24 Examples 25 Pack and unpack 26 27 Collective Communication 28 Intro duction and Overview 29 Communicator argument 30 Barrier synchronization 31 Broadcast 32 Example using MPI BCAST 33 Gather 34 Examples using MPI GATHER MPI GATHERV 35 Scatter 36 SCATTER MPI SCATTERV Examples using MPI 37 Gathertoall 38 Examples using MPI ALLGATHER MPI ALLGATHERV 39 AlltoAll ScatterGather 40 Global Reduction Op erations 41 Reduce 42 Predened reduce op erations 43 MINLOC and MAXLOC 44 UserDened Op erations 45 AllReduce 46 ReduceScatter 47 Scan 48 Example using MPI SCAN 1 Correctness 2 3 Groups Contexts and Communicators 4 Intro duction 5 Features Needed to Supp ort Libraries 6 MPIs Supp ort for Libraries 7 Basic Concepts 8 Groups 9 Contexts 10 IntraCommunicators 11 Predened IntraCommunicators 12 Group Management 13 Group Accessors 14 Group Constructors 15 Group Destructors 16 Communicator Management 17 Communicator Accessors 18 Communicator Constructors 19 Communicator Destructors 20 Motivating Examples 21 Current Practice .