OPENJDK.textile


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h1. OpenJDK FCS Release for AArch64

The 14.07 release of OpenJDK is a fully functional, stable release of OpenJDK. It has been extensively tested using test suites including the "JTREG":http://openjdk.java.net/jtreg/, JCK and "Mauve":http://www.sourceware.org/mauve/ test suites as well as real work applications such as Hadoop, Eclipse and industry standard benchmarks such as SPECjvm2008 and PECjbb2013. There are no known critical failures when used with standard options. There are a number of failures when used with certain non standard options. These failure are detailed below.

The release is being made available in two variants:

h2. OpenJDK 8

The OpenJDK 8 release is based on the jdk8-b132 tag of the main OpenJDK 8 "tree":http://hg.openjdk.java.net/jdk8/jdk8. This corresponds to the "General Availability" release announced on "2014/03/18":http://openjdk.java.net/projects/jdk8.

h2. OpenJDK 7

As JDK8 is a complete revision of JDK, a backport to OpenJDK 7 is provided for compatibility with the known and proven JDK7. This release is based on the jdk7u60-b04 tag of the JDK7 updates "tree":http://hg.openjdk.java.net/jdk7u/jdk7u.

h2. Supported HotSpot Technologies

Both OpenJDK releases support the Client (C1) and Server (C2) JIT compilers in addition to supporting the Template assembler based interpreter and the 'Zero' C based interpreter.

The default execution model is Server (C2) JIT using Tiered Compilation. Under this model code is first executed by the Template nterpreter. When code is deemed to be 'hot' it is compiled initially using the Client (C1) JIT. The code compiled by the C1 JIT contains profiling code. If a method is deemed to be sufficiently hot it is recompiled with the Server (C2) JIT. The C2 JIT uses the profiling information collected by the C1 JIT to generate highly optimal execution path targetted code.

Different execution models may be selected using the following command line options.

* -server - The default Server (C2) JIT
* -client - The Client (C1) JIT
* -Xint - The Template assembler based interpreter
* -zero - The 'Zero' C based interpreter

In addition the following options may be specified

* -XX:+TieredCompilation
*** The default with -server. Enable Tiered compilation as described above.
* -XX:-TieredCompilation
*** Disable Tiered compilation. Code is compiled directly with the Server (C2) JIT. Using this option will generate less efficient code because the profiling information gathered by the C1 compiler will not be available.

h2. Source and binary bundles

Source bundles may be downloaded from:

* "OpenJDK 8":http://openjdk.linaro.org/archives/fcs/source/jdk8_fcs.tgz

* "OpenJDK 7":http://openjdk.linaro.org/archives/fcs/source/jdk7_fcs.tgz

Pre-built binaries may be downloaded from:

* "OpenJDK 8":http://openjdk.linaro.org/archives/fcs/binary/jdk8_image.tgz

* "OpenJDK 7":http://openjdk.linaro.org/archives/fcs/binary/jdk7_image.tgz

h2. Test Results

There are two categories of tests run on a daily basis.

h3. Lava Testing

These tests are run on the foundation model. Because of the performance limitations of the foundation model a limited subset of the JTreg and Mauve test suites are run daily.

"Results":https://validation.linaro.org/dashboard/image-reports/leg-java-armv8 are published daily.

h3. Hosted Testing

These tests are run on ARMv8 hardware which is hosted in our Cambridge lab but is not publicly available in LAVA. The entire JTreg test suite is run on a daily basis for both Client and Server JITs.

Results are published by email to aarch64-port-dev@openjdk.java.net. This email list may be subscribed to by visiting:

* "E-mail subscription":http://openjdk.java.net/projects/aarch64-port

Note: that for the hosted tests, if the daily test determines that there has been no change to the source tree then the tests are not run. This is done to reduce bandwidth on the email list.

Note: In spite of the slowness of the tests executed on the foundation model, which prevents complete test execution on a daily basis, we periodically verify that the complete test execution provides the very same identical results on both the foundation model and the real h/w in our lab. Please note that no performance numbers are posted to the mailing lists, only functional pass/fail test results.

h2. Known Failures

h3. -XX:+UseBiasedLocking causes a fatal error

* The implementation of Biased Locking has not been completed in the AArch64 port and use of this option may cause fatal errors.

Workaround: Do not use the -XX:+UseBiasedLocking option.

h3. Assertion failure with -XX:-InlineObjectHash and -XX:-ProfileInterpreter

This combination of options may cause the following fatal error to be generated:

* assert(false) failed: this call site should not be polymorphic

Workaround: Do not use this combination of options.

h2. Acknowledgements

We would like to thank RedHat, and especially Andrew Haley and Andrew Dinn, for starting this project and for the huge efforts they have put in to deliver a high quality, high performance Java solution for AArch64 which is available as Open Software. We would also like to thank all in the Open Source community who have contributed to the projects, either through bug fixes or suggestions or through testing early releases of the software and submitting bug reports.