Re: t and nil in pure memory?

[Stefan Monnier]

> There are lots of changes, major or minor, that might be worth exploring.
> Prefetching, putting mark bits on different words or  pages, tri-color
> schemes, incremental marking, generational GC, etc.,  etc.  But maybe we
> should also consider a more drastic change: Use  Hans Boehm's GC library.

It's definitely worth exploring.  IIRC the main problem with it was how
to get the necessary pointer-weakness where we expect it (hash-tables,
markers, undo-lists, and a couple others I can't remember), and of
course add the relevant hooks to get back the GC-precision we currently
enjoy.  Oh, and of course, we'd need to compare the performance (memory
use and CPU use, mostly) to make sure it doesn't get worse.  I'd expect
the memory use to go up slightly, not sure about the performance.
It likely would improve our vector-allocation performance (which
currently sucks).
Also we'd need to decide what to do about the platforms not supported by
the Boehm GC.


        Stefan