I was thinking on ways that functional languages could be more tied directly to their hardware and was wondering about any hardware implementations of garbage collection.
This would speed things up significantly as the hardware itself would implicitly handle all collection, rather than the runtime of some environment.
Is this what LISP Machines did? Has there been any further research into this idea? Is this too domain specific?
Thoughts? Objections? Discuss.
Because of Generational Collection, I'd have to say that tracing and copying are not huge bottlenecks to GC.
What would help, is hardware-assisted READ barriers which take away the need for 'stop the world' pauses when doing stack scans and marking the heap.
Azul Systems has done this: http://www.azulsystems.com/products/compute_appliance.htm They gave a presentation at JavaOne on how their hardware modifications allowed for completely pauseless GC.
Another improvement would be hardware assisted write barriers for keeping track of remembered sets.
Generational GCs, and even more so for G1 or Garbage First, reduce the amount of heap they have to scan by only scanning a partition, and keeping a list of remembered sets for cross-partition pointers.
The problem is this means ANY time the mutator sets a pointer it also has to put an entry in the appropriate rememered set. So you have (small) overhead even when you're not GCing. If you can reduce this, you'd reduce both the pause times neccessary for GCing, and overall program performance.