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From "Weldon Washburn" <weldon...@gmail.com>
Subject Re: [drlvm][sablevm] Desing of Class Unloading Support
Date Tue, 31 Oct 2006 21:47:01 GMT
On 10/31/06, Etienne Gagnon <egagnon@sablevm.org> wrote:
> Yet:
> 1- You do need pinning, so you rule out some of the simplest GCs (e.g.
> simple, non-generational copying without pinning.)  [Apparently, for
> some very large heaps, simple copying a can be quite difficult to beat,
> efficiency wise, if you believe some relatively recent JikesRVM related
> paper...]
> 2- You do have overhead even on minor collections.  With my approach,
> you could limit the (quite similar to yours, if you put a
> class-loader/NULL pointer in the vtable) overhead only to selected GC
> cycles.
> Of course, I am sure that all of the proposed approaches have their
> benefits/drawbacks.  I was simply contributing to the ongoing
> discussion.  I have no special reason to try very hard to convince you
> that "my idea is better than yours"!  I'm only joining the debate for
> trying find the most suitable solution.  I've already gained knowledge,
> from the discussion so far, that I'll be able to apply eventually in
> SableVM. :-)
> Maybe the best solution lies in mixing some of the various ideas
> proposed so far...

I too learned a lot from this thread.  I also suspect a better solution will
emerge from these kinds of discussions.

> Ivan Volosyuk wrote:
> > Actually, no need to add the overhead to _all_ cycles. We don't need
> > to trace the vtables everytime. On minor collections all the pinned
> > vtables can be linearly scanned, thus most expensive tracing from
> > object to vtable can be avoided in this case.
> >
> --
> Etienne M. Gagnon, Ph.D.            http://www.info2.uqam.ca/~egagnon/
> SableVM:                                       http://www.sablevm.org/
> SableCC:                                       http://www.sablecc.org/

Weldon Washburn
Intel Enterprise Solutions Software Division

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