Enabling Java: Windows on Arm64 - A Success Story!
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The document provides an overview of Microsoft's efforts to port OpenJDK to Windows on Arm64. It discusses the background of OpenJDK and Arm64, details of the port including Windows and Arm64 specific nuances, and the timeline of the port from initial work to current testing and benchmarking efforts. It also introduces the team behind the port and highlights some of their key learnings and accomplishments.
Enabling Java: Windows on Arm64 - A Success Story!
- 1. Enabling Java: Windows on Arm64 – A Success Story! @mon_beck By: Monica Beckwith
- 2. Agenda Introduction to OpenJDK & Arm64 About Our Port Background Windows and Arm64 Nuances Timeline Testing and Benchmarking Next Steps It’s Demo Time!
- 3. Introduction to OpenJDK & Arm64
- 4. What is The OpenJDK Project? Open Java Development Kit • Free and open source reference implementation of Java SE (Standard Edition) • Licensed under GNU GPL version 2 with Classpath Exception 2006 OpenJDK Timeline Java HotSpot Virtual Machine 2007 Almost all the Java Development Kit 2010 100% of the Java Development Kit
- 5. The OpenJDK Community Getting Involved Is Caring 2006 OpenJDK Timeline Java HotSpot Virtual Machine 2007 Almost all the Java Development Kit 2010 100% of the Java Development Kit RedHat signs the Sun/Oracle Contributor Agreement and TCK License Agreement Porters Group created to extend OpenJDK on different processor architectures and OSes IBM, Apple SAP join the OpenJDK Community Microsoft 2013 +
- 6. What is Arm? RISC-y Business? • Reduced Instruction Set Computer • Highly optimized instruction set • Large number of registers • Load/Store architecture: Memory Data Processing Instructions
- 7. Memory Access Instructions What is Arm? RISC-y Business? • Reduced Instruction Set Computer • Highly optimized instruction set • Large number of registers • Load/Store architecture: • Memory accessed via specific instructions • E.g. LDR Rt, <addr> where Rt is the integer register Processor Register Memory
- 8. What is Arm64 aka AArch64? What's in a Name? • 64-bit ISA • 64-bit wide int registers, data and pointers • Weak Memory Model with Multiple Copy Atomicity • Barriers/fences are needed for access ordering • E.g. ISBs – instruction flushes the CPU pipeline, etc • E.g. One-way barriers (LDARs, etc) inline void OrderAccess::loadload() { acquire(); } inline void OrderAccess::storestore() { release(); } inline void OrderAccess::loadstore() { acquire(); } inline void OrderAccess::storeload() { fence(); } #define READ_MEM_BARRIER atomic_thread_fence(std::memory_order_acquire); #define WRITE_MEM_BARRIER atomic_thread_fence(std::memory_order_release); #define FULL_MEM_BARRIER atomic_thread_fence(std::memory_order_seq_cst); inline void OrderAccess::acquire() { READ_MEM_BARRIER; } inline void OrderAccess::release() { WRITE_MEM_BARRIER; } inline void OrderAccess::fence() { FULL_MEM_BARRIER; }
- 9. Arm64 ISA and Third-Party Systems The More, The Merrier Arm64 ISA Timeline Arm v8 eMAG system Arm v8.1 ThunderX2 system Arm v8.2 Surface Pro X system Arm v8.3 …. Ampere Computing’s product. Also known as Applied Micro’s XGene3 and Skylark Cavium Inc.’s product. Now owned by Marvell Technology Group Microsoft and Qualcomm’s collaboration – SQ1&2 processors …
- 10. About Our Port Background Windows & Arm64 Nuances Timeline
- 11. What is an OpenJDK Port? Write Once Run Anywhere... ? • Windows on Arm64 is a new platform for OpenJDK • In order to be able to develop in Java, we need to get the JDK to work on the new platform • In-order to run Java applications on this new platform, we need to get the Java Runtime Environment (JRE) to work on it. • A JDK is a superset of a JRE as it includes tools and utilities for development and debugging Java HotSpot VM A JRE Class Libraries Runtime Execution Engine UI Toolkits Base, Lang, Util Libs
- 12. Quick Overview of HotSpot What’s in a VM? • Most of the code is non-OS and non-Arch specific • E.g. Memory Management, Compilers, Metadata, etc • Rest is organized as follows: • Architecture specific code • E.g. AArch64, x86 … • OS specific code • E.g. Windows, Linux … • OS and Architecture specific code • E.g. Windows_AArch64, Linux_AArch64 … HotSpot Source Repo Share CPU OS OS_CPU
- 13. What is a Runtime? Bytecode to Native Code • Classloading, Interpretation, Bytecode verification, Exception Handling, Thread Management, Synchronization • Our changes: JDK Launcher for JVM creation, destruction to use structured exception handling on Windows Java HotSpot VM Runtime Execution Engine Execution Engine
- 14. What is an Execution Engine? A Smart, Adaptive, Profile Guided Orchestrator… • Compilation and Heap Management • Most of our changes were in the execution engine to enable Arm64 architecture specific changes for Windows and adding Windows-Arm64 specific changes for HotSpot in general Java HotSpot VM Runtime Execution Engine Runtime
- 15. Windows and AArch64 Specific Learnings What’s in a Register? • Register R18 is a platform register and has special meanings for kernel and user mode • We need to avoid using it for HotSpot purposes and treat is as “Reserved” • Invalidating instruction cache R18 = non_allocatable_reg Flushing a range of bytes in ICache // Interface for updating the instruction cache. Whenever the VM modifies code, part of the processor // instruction cache potentially has to be flushed. class ICache : public AbstractICache { <snip> static void invalidate_range(address start, int nbytes) { FlushInstructionCache((HANDLE)GetCurrentProcess(), start, (SIZE_T)(nbytes)); } };
- 16. Windows and AArch64 Specific Learnings Features, features, everywhere! • Cache line size optimized assembly stubs for copying • CPU features detection such as AES, CRC32, etc void VM_Version::get_os_cpu_info() { if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE)) _features |= CPU_CRC32; if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE)) _features |= CPU_AES | CPU_SHA1 | CPU_SHA2; if (IsProcessorFeaturePresent(PF_ARM_VFP_32_REGISTERS_AVAILABLE)) _features |= CPU_ASIMD; … CPU features detection Platform optimized byte swaps and copy stubs
- 17. Windows and MSVC Specific Learnings Intrinsics Fun • Atomic Read-Write barriers and functions such as CompareExchange • MSVC offers various intrinsics and we employed those • E.g. __nop() MSVC Intrinsics #ifdef __GNUC__ // __nop needs volatile so that compiler doesn't optimize it away #define NOP() asm volatile ("nop"); #elif defined(_MSC_VER) // Use MSVC instrinsic: https://docs.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=vs-2019#I #define NOP() __nop(); #endif Platform friendly Intrinsics for Atomic functions
- 18. Windows and MSVC Specific Learnings Would the real 64-bit please stand up!? LP64 vs LLP64 issues: Extending 64-bit long integers and pointers to the long-long integers and pointers needed by the 64-bit Windows platform • Most Unix-like systems (Linux, macOS, etc) follow the LP64 data model • Windows follows the LLP64 model LP64 vs LLP64 data models LP64 LLP64 short 16 16 int 32 32 long 64 32 long long 64 64 size_t, pointers 64 64
- 19. Meet Us and Our Port The Trifecta Feb 2020 Port Timeline $ bin/java.exe –version works! # Java VM: OpenJDK 64- Bit Server VM (fastdebug 15- internal+… windows- aarch64) Mar 2020 Core Dump Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020 Oct 2020 eMAG system
- 20. Meet Us and Our Port The Trifecta Feb 2020 Port Timeline Mar 2020 Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020 Oct 2020 Great Collaboration with the MSVC team eMAG system ThunderX2 system Surface Pro X system JTReg tier 1 testing, JMH subset runs and JVM2008 + JBB2015 subset runs
- 21. Meet Us and Our Port The Trifecta Feb 2020 Port Timeline Mar 2020 Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020 Oct 2020 eMAG system Parts of SPEC SERT work with C1 and Parallel GC Benchmark mods needed for JNI and >64 cores identification on Windows C2 is functional SPEC SERT changes made Full scale testing underway ThunderX2 system Surface Pro X system
- 22. Meet Us and Our Port The Trifecta Feb 2020 Port Timeline Mar 2020 Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020 Oct 2020 eMAG system Start discussions with RedHat on the patches ThunderX2 system Surface Pro X system Fixed G1 GC – Introduced a workaround Patches surfaced on OpenJDK and first EA build released Exception handling bug fixed for Swing and Java 2D + Surface Pro X
- 23. Meet Us and Our Port The Trifecta Feb 2020 Port Timeline Mar 2020 Apr 2020 May 2020 Jun 2020 Jul 2020 Aug 2020 Sep 2020 Oct 2020 eMAG system ThunderX2 system Surface Pro X system JEP drafted JEP became a Candidate SPEC SERT changes approved All three of us became Committers to OpenJDK AArch64 Project All GCs enabled and heap + JVM scaling tests completed JDK 16 targeted We are OpenJDK!
- 25. Testing Setup & CI • We divided our changes into incremental patch sets and made sure that they cleanly apply to tip. • We tested the patches incrementally on Linux/AArch64, Windows/AArch64, Windows/x64, and, only for functional testing, Linux/x64. • We enabled CI for JTReg tests on our patches on the test platforms Phases Windows + AArch64 Linux + AArch64 Windows + X86-64 (VMs OK) Linux + X86-64 (VMs OK) Phase 1 hotspot:tier 1, jdk:tier1 and langtools hotspot:tier 1, jdk:tier1 and langtools hotspot:tier 1, jdk:tier1 and langtools hotspot:tier1 , jdk:tier1 and langtools Phase 2 - hotspot:all, jdk:all and langtools hotspot:all, jdk:all and langtools hotspot:all, jdk:all and langtools Phase 3 hotspot:all, jdk:all and langtools - - - Phase 4 JTReg + GTests + Adopt QA tests JTReg + GTests + Adopt QA tests JTReg + GTests + Adopt QA tests JTReg + GTests + Adopt QA tests
- 26. Testing Setup & CI • We divided our changes into incremental patch sets and made sure that they cleanly apply to tip. • We tested the patches incrementally on Linux/AArch64, Windows/AArch64, Windows/x64, and, only for functional testing, Linux/x64. • We enabled CI for JTReg tests on our patches on the test platforms Test system Hardware Patch combo hbIR max hbIR settled max- JOPS critical- JOPS linux- aarch64 TX2 P1 100% 98% 94% 49% linux- aarch64 TX2 P1 + P2 100% 97% 94% 50% windows -aarch64 TX2 P1 + P2 100% 88% 83% 40% windows -x86-64 Skylake P1 100% 90% 85% 27% windows -x86-64 Skylake P1 + P2 100% 90% 85% 27%
- 27. Our Workload Status and Benchmark Matrix Workload Tests Arm64 Status Comments Java Regression Testing Framework (JTREG) hotspot:all, jdk:all and langtools o* We will soon include Gtests and Adopt QA tests Java Micro Benchmark Harness (JMH) many microbenchmarks used for performance and implementation testing o* we ran the 'jmh-jdk-microbenchmarks' suite on our test platforms and found no significant issues SPEC JBB2015 o* Performance studies with newer GCs still WIP SPEC JBB2005 o* Performance studies with newer GCs still WIP SPEC JVM2008 crypto, xml, derby, compress, etc o* startup doesn't work on JDK8+ SPEC SERT o Benchmark changes made to accommodate the new platform combo, up-streamed to SPEC DaCapo Benchmark avrora fop h2 jython luindex lusearch lusearch-fix pmd sunflow tomcat xalan o* one benchmark utilizes an x86-64 dll. A few others don't work on JDK8+. Lower priority VSCode o Minecraft Server o Legend Status o Complete o* Almost there, see notes x Incomplete
- 28. Next Steps
- 29. Next Steps The journey has just started … • macOS + AppleSi port • Collaboration with Azul • Learnings from Windows port: R18, CPU feature detection, etc. • RFE: https://github.com/openjdk/aarch64-port/pull/2 • JVMCI and AOT in HotSpot • RFE: https://github.com/openjdk/jdk/pull/685 • Backport to JDK11 for Windows and macOS • RFE: https://github.com/openjdk/aarch64-port/tree/jdk11-windows Keep the port up-to- date Working closely with the Windows Memory Management team Working closely with the MSVC team
- 30. It’s Demo* Time! https://github.com/microsoft/ openjdk-aarch64/releases Download and Take it for a Spin *https://spring.io/guides/gs/spring-boot/
- 32. Thank You! https://github.com/microsoft/ openjdk-aarch64/releases Download and Take it for a Spin Our GitHub Repo: https://github.com/microsoft/openjdk-aarch64 Our OpenJDK PR: https://github.com/openjdk/jdk/pull/212 A few announcements: https://devblogs.microsoft.com/java/announcing-openjdk-windows-arm/ https://www.infoq.com/news/2020/08/openjdk-win10-arm/ https://www.infoq.com/news/2020/09/microsoft-windows-mac-arm/
Editor's Notes
- #3: We will provide: 1) a quick timeline of our development efforts and Microsoft’s journey into OpenJDK land (spoiler alert: we were welcomed with open arm(s) (pun intended)), 2) a few Arm64 and Windows nuances, 3) our testing and benchmarking North Stars. If we feel lucky, we will even showcase a demo on our Surface Pro X device.
- #18: ProcessthreadsAPI.h
- #19: ProcessthreadsAPI.h Interlockedcompare exchg intrinsic
- #33: Talk about community