Data Parallel C++ Mastering DPC++ for Programming of Heterogeneous Systems using C++ and SYCL Chapters 1-4 UNEDITED ADVANCE REVIEW COPY Ben Ashbaugh, James Brodman, Michael Kinsner, John Pennycook, Xinmin Tian, and James R. Reinders Data Parallel C++: Mastering DPC++ for Programming of Heterogeneous Systems using C++ and SYCL Copyright © 2020 by Intel Corporation This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. ISBN-13 (pbk): TBA ISBN-13 (electronic): TBA Trademarked names, logos, and images may appear in this book. 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For more detailed information, please visit http://www.apress.com/source-code ii Table of Contents Chapter 1 - Introduction ............................................................................... 1 What is Data-Parallel Programming? ....................................................................... 2 What are Heterogeneous Systems? .......................................................................... 3 Enjoy the Journey – This is something BIG ................................................................ 4 Parallel Programming in C++ .................................................................................... 4 Journey to Parallelism, Scaling, Portability ............................................................... 4 First look at DPC++ code ............................................................................................ 6 Why DPC++? .............................................................................................................. 6 Why must it be a first-class citizen? ................................................................................. 8 Made for each other: Data parallelism and Big Data ........................................................ 8 SYCL, DPC++, C++ ....................................................................................................... 9 Khronos SYCL .................................................................................................................... 9 DPC++ ............................................................................................................................... 9 C++ ................................................................................................................................. 10 Why Heterogeneous Systems? ................................................................................ 11 Platform Model .............................................................................................................. 13 Multiarchitecture (aKa “Fat”) Binaries ............................................................................ 14 Compilation Model ......................................................................................................... 14 Truth and Fallacy of Write Once, Run EVeryWhere ......................................................... 15 Direct programming ....................................................................................................... 17 Why Data Parallelism? ............................................................................................ 18 ThinK (Data) Parallel ....................................................................................................... 18 Intranode, not multinode, parallelism .................................................................... 19 Other Accelerator Programming Models ................................................................ 19 Evolution of SYCL (thus far) ..................................................................................... 22 iii TABLE OF CONTENTS March 2015 – SYCL 1.2 .................................................................................................... 22 April 2019 – SYCL 1.2.1r5 ................................................................................................ 23 SYCL 1.2.1r6 and beyond ................................................................................................ 23 SYCL Provisional 2.2 ........................................................................................................ 23 Chapter 2 – Where Code Executes ......................................................... 25 Single source ........................................................................................................... 25 Host code........................................................................................................................ 26 DeVice code .................................................................................................................... 27 Choosing a device on which to execute ................................................................... 28 Method#1: Just run on a device (don’t care what type) .......................................... 28 Queues ..........................................................................................................................