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From "Weldon Washburn" <weldon...@gmail.com>
Subject Re: [DRLVM] proposal to port MMTK to drlvm
Date Wed, 24 May 2006 21:00:04 GMT
On 5/24/06, Ivan Volosyuk <ivan.volosyuk@gmail.com> wrote:
> I have a patch for drlvm which enables use of write barriers. This
> works in interpreter mode only yet. I can put it on jira if somebody
> is interested.
This is helpful.  Please post the patch.  I will take a look at it
sometime soon.
Thanks

>The write barriers are tested with an algorithm which
> does per-slot validation and should work fine.
> --
> Ivan
>
> 2006/5/24, Daniel Feinberg <csdread@gmail.com>:
> > > >My understanding of write barriers is as an optimization.
> > > That fits with my understanding of write barriers also.   I do not
> > > know for certain but suspect that MMTK can somehow be configured such
> > > that write barriers are not required for correctness.  Maybe Dan
> > > Feinberg can tell the mailing list.
> >
> > So MMTK is a toolkit for building GCs. When doing generational
> > collection the write barrier is used to keep track of pointers that go
> > from older generations to yonger generations. You must have a way to
> > track these objects because when you do a partial heap collection (aka
> > just the nursery or nursery and old1) you need to build a root set of
> > all things that point into that space. Then you trace this root set to
> > find all live objects that need to be moved to an older generation. In
> > other methods of collecting the write barrier is not as important.
> > Here unless you can find all of these pointers that point into a space
> > from an older space you must use a write barrier.
> >
> >
> > Daniel
>
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>


-- 
Weldon Washburn
Intel Middleware Products Division

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