JVMs and the new silicon

[Benoît Paris]

Hello all!

I'm seeing more and more news about new exotic silicon pushing code closer to the data, and I was wondering what was the future of JVMs in all this.

As an example: Upmem is starting to offer some RAM with compute capabilities. They claim 2TB/s of RAM-compute-RAM bandwidth for a 128GB set. The low level API seems to be an LLVM backend and code close to a map operation: for each chunk of computing ram, send a tasklet for a local computation.

I have lots of questions:

* Are Java and the JVMs suited to make good use of that hardware?

* What's the mechanically sympathetical API to it? Are map operations in Parallel Streams a good abstraction?

* Surely the results must be stored locally, within each RAM chunk. What would automated memory management look like with this? Is it per RAM chunk, can it be global? Is there a need for rebalancing/shuffling data between RAM chunks?

* Are we going to see it at all on JVMs? What's the integration cost? Do you translate Java bytecode to LLVM to use their backend? Can it be done through the upcoming Vector API?

Cheers

Ben

[Peter Veentjer]

The track-record of Java isn't very good IMHO. For example:

1) the Hotspot JVM isn't very good at identifying where SIMD instructions should be used (Azul Zing with the LLVM backend does a better job).

2) There is no official integration for GPGPU (General-Purpose computing on Graphics Processing Units) even though powerful GPU's are everything but rare.

3) Support for hardware transactional memory

4) Hardware accelerated encryption; although Java finally caught up in Java 11.

5) Memory layout of objects

6) record types (to reduce the overhead of objects)

So based on that I would not be surprised if official integration would be added very late if added at all.

[Wojciech Kudla]

Although I generally agree with the sentiment of Java's poor track record when it comes to early support for stuff like SIMD or GPGPU, Graal VM looks very promising.

Firstly, there's a lot of relatively recent developments happening in the area of optimisations, eg: https://github.com/oracle/graal/pull/1692

Secondly, Graal VM has matured enough to become an official offering from Oracle: https://www.oracle.com/uk/tools/graalvm-enterprise-edition.html

There's also freely available community edition with some extra optimisations missing.

It looks like the future is not that bleak.

--
You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group.
To unsubscribe from this group and stop receiving emails from it, send an email to mechanical-symp...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/mechanical-sympathy/db3bcaca-e68a-4085-9123-853c001eb0f6%40googlegroups.com.

[Kevin Bowling]

OpenJ9 does almost all of these things

--