The Weekly Squeak

Eliot Miranda has announced that his new Cog VM is now available for download, bringing Just-In-Time compilation and massive speed-ups to Squeak and Pharo.

If you’ve been following Eliot’s blog, you’ll know that he’s been working on this new VM for quite a few months now; well, it’s now ready for public consumption, and it’s blisteringly fast: up to three times faster than the existing VMs.

The VM selectively re-compiles code to native (Intel) machine-code, based on the size and complexity of the methods, and how often they’re called. This means that the benefits of the new VM vary from task to task, but Andreas Raab estimates that you should expect a 2-3x performance improvement generally, “more towards 2x when running primitive and I/O-bound stuff; more towards 3x when running ‘pure’ Smalltalk code”.

Eliot is interested in hearing from developers on other platforms who want to port the new VM to those platforms. In the meantime, he has also released the “Stack VM”, a cross-platform interpreter that uses context-to-stack mapping to achieve more modest performance gains.

See Eliot’s original post and the following discussion for more details of the new VM, some notes of caution, and how to get your hands on it and use it.

Thanks to Eliot for this great piece of work, and to Teleplace who have funded this work (and have been using it for the past year), and have agreed to release the new VM’s under the MIT Licence.