MMTk-OpenJDK

This repository provides binding between MMTk and OpenJDK.

Contents

• Requirements
• Build
• Test

Requirements

We maintain an up to date list of the prerequisite for building MMTk and its bindings in the mmtk-dev-env repository. Please make sure your dev machine satisfies those prerequisites.

Before you continue

If you use the set-up explained in mmtk-dev-env, make sure to set the default Rust toolchain to the one specified in mmtk-dev-env, e.g. by running:

# replace nightly-YYYY-MM-DD with the the toolchain version specified in mmtk-dev-env
$ export RUSTUP_TOOLCHAIN=nightly-YYYY-MM-DD

You may also need to use ssh-agent to authenticate with github (see here for more info):

$ eval `ssh-agent`
$ ssh-add

Getting Sources (for MMTk and VM)

First, clone this binding repo:

$ git clone --recursive --remote-submodules [email protected]:mmtk/mmtk-openjdk.git

The mmtk-openjdk binding repo is located under the mmtk folder, as a git-submodule of the OpenJDK repo.

The mmtk-core crate is a cargo dependency of the mmtk-openjdk binding repo.

The openjdk repo is at ./repos/openjdk. And ./openjdk contains mmtk's ThirdPartyHeap implementation files.

Build

Note: MMTk is only tested with the server build variant.

After cloned the OpenJDK repo, cd into the root directiory:

$ cd mmtk-openjdk/repos/openjdk

Then select a DEBUG_LEVEL, can be one of release, fastdebug, slowdebug and optimized.

$ # As an example, here we choose to build the release version
$ DEBUG_LEVEL=release

The differences between the four debug levels are:

$DEBUG_LEVEL	Debug Info	Optimizations	Assertions	MMTk Cargo-Build Profile
release	✘	✔	✘	release
optimized	✘	✔	✘	debug
fastdebug	✔	✔	✔	debug
slowdebug	✔	✘	✔	debug

If you are building for the first time, run the configure script:

$ sh configure --disable-warnings-as-errors --with-debug-level=$DEBUG_LEVEL

Then build OpenJDK (this will build MMTk as well):

$ make CONF=linux-x86_64-normal-server-$DEBUG_LEVEL THIRD_PARTY_HEAP=$PWD/../../openjdk

The output jdk is at ./build/linux-x86_64-normal-server-$DEBUG_LEVEL/jdk.

Location of Mark-bit

The location of the mark-bit can be specified by the environment variable MARK_IN_HEADER. By default, the mark-bit is located on the side (in a side metadata), but by setting the environment variable MARK_IN_HEADER=1 while building OpenJDK, we can change its location to be in the object's header:

$ MARK_IN_HEADER=1 make CONF=linux-x86_64-normal-server-$DEBUG_LEVEL THIRD_PARTY_HEAP=$PWD/../../openjdk

Test

Run HelloWorld (without MMTk)

$ cat ./HelloWorld.java
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}
$ ./build/linux-x86_64-normal-server-$DEBUG_LEVEL/jdk/bin/javac HelloWorld.java
$ ./build/linux-x86_64-normal-server-$DEBUG_LEVEL/jdk/bin/java HelloWorld
Hello World!

Run DaCapo Benchmarks with MMTk

First, fetch DaCapo:

$ wget https://sourceforge.net/projects/dacapobench/files/9.12-bach-MR1/dacapo-9.12-MR1-bach.jar/download -O ./dacapo-9.12-MR1-bach.jar

Run a DaCapo benchmark (e.g. lusearch):

$ ./build/linux-x86_64-normal-server-$DEBUG_LEVEL/jdk/bin/java -XX:+UseThirdPartyHeap -Xms512M -Xmx512M -jar ./dacapo-9.12-MR1-bach.jar lusearch
Using scaled threading model. 24 processors detected, 24 threads used to drive the workload, in a possible range of [1,64]
===== DaCapo 9.12-MR1 lusearch starting =====
4 query batches completed
8 query batches completed
12 query batches completed
16 query batches completed
20 query batches completed
24 query batches completed
28 query batches completed
32 query batches completed
36 query batches completed
40 query batches completed
44 query batches completed
48 query batches completed
52 query batches completed
56 query batches completed
60 query batches completed
64 query batches completed
===== DaCapo 9.12-MR1 lusearch PASSED in 822 msec =====

Note: Pass -XX:+UseThirdPartyHeap as java command line arguments to enable MMTk.