Mimalloc Port (Free List Allocator and Mark Sweep Space)

[paigereeves]

The goal is to have an implementation of malloc/free based on mimalloc.

Free List Allocator

• Thread-local lists of owned 64kB blocks. Separated (possibly implicitly) into available, exhausted, and unswept blocks.
• Segregated size classes.
• Eager or lazy sweeping.
• A method to sweep a marked block by constructing a free list.
• (Lazy) allocate to unswept blocks by constructing free lists as required and moving swept blocks to the available list.
• (Lazy) allocation is attempted first from a thread's available list, then its unswept list, then other threads' unswept lists, then fresh memory from the associated space.
• Reconstruct thread-local block lists after marking.
• A global list of all active 64kB blocks in that space, used for stealing unswept blocks from other threads.

Mark Sweep Space

• Referencing the old MMTk's MarkSweepSpace policy, but excluding any functionality including free lists and size classes, for example, which are considered utility and exist within the allocator.
• Send a signal to allocator threads when marking is completed.
• Should be able to replace this with a (yet unimplemented) reference counting policy without any changes from the allocator's side.