On May 1, 2:07 pm, "Kjetil S. Matheussen" <k.s.matheus...@[EMAIL PROTECTED]
>
wrote:
> Sweep may run in parallel, I just chose it not too. It might
> be faster to make it run in parallel, but it requires locks
> around alloc() and free(), which will also slow down, so maybe not.
> Benchmarking is needed to find that out. Its possible to have
> two heaps though, and free in one while allocating in another,
> but that will cause more memory fragmentation, plus that
> all memory can't be freed anyway, which is the only real advantage
> of running sweep in parallel using locks around free() (ie.
> theres less chance of running out of memory and therefore the heap size
> can be decreased), so there's probably not really much advantage
> in having two heaps either.
>
> The advantage of not having write barriers is obvious: write barriers
> are complicated and the code having to deal with them will
> use more cpu.
I don't mean to criticize. It is not clear to me under what
circumstances copying the entire heap (including the dead blocks)
becomes cheaper than using write barriers, but as I said I am not
familiar with sound processing and its requirements.
If the goal is to use GC without compiler cooperation (e.g. in C) and
still get real-time benefits, then the advantages are clear.
>
> > Is the idea that atomic copying of the heap is cheaper than "atomic
> > marking of the roots + plus write barriers" which is otherwise
> > required?
>
> Don't know. Probably. The point about this garbage collector
> is that its very simple to plug into most garbage producing
> high level languages which uses mark and sweep collectors.
Got it. Thanks for the explanations.
> I don't know what you are trying to achieve, but if its only
> better interactivity you're after, generational garbage collectors
> seems to do a pretty good job.
Actually that is a common misconception. Generational collectors only
postpone the problem because sooner or later they need to do a full GC
cycle. Interactivity should be dealt with as a hard real-time problem.
Unfortunately none of the existing languages and UI frameworks are
doing anything substantial (or at all) in that direction. Python with
its reference counting may currently be the best language for UI.
regards,
Tzvetan
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