[Timber] GC questions

[Ivan Tarasov]

1. Is there any good description of GC used on POSIX and on ARM? Why
is the code for the GCs different (and could it be shared)?
2. Is there explanation of possible effects of the GC on real-timeness
of the application in Timber? That looks like an important point to
consider before embarking on writing real-time control in Timber.
3. (from my quick look at the rtsARM/gc.c) It looks like the GC only
starts to work after the heap is 13/16 full. If that's true, I'm not
sure it's the best policy: the processor may be cycle idly while it
could have been collecting garbage (when the next planned event is not
going to happen too soon). Thus when the event happens, it may get
unnecessarily constrained by the small amount of free heap left.

Ivan