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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [DRLVM][GC] high-level design proposal for GCV5
Date Fri, 25 Aug 2006 10:39:42 GMT
Ivan, Salikh, good idea and thanks for the info. We'd want to apply
the work into Harmony GC.

Thanks,
xiaofeng


On 8/25/06, Salikh Zakirov <Salikh.Zakirov@intel.com> wrote:
> Ivan Volosyuk wrote:
> > Yes, I have experimented with per-slot verification of write barrier.
> >
> > The idea was the following: each word in java heap has external mirror
> > record. After garbage collection all mirror records are synchronized
> > with the heap. Each write barrier updates mirror record with
> > corresponding data. Before next garbage collection there is a trace
> > for all reachable objects in heap which validates that each slot
> > contains the same data as the mirror.
> >
> > The idea is quite simple. Even that, it helped my find number of
> > places in VM code which have updated slots in heap without call to
> > write barrier. The results of the work are in HARMONY-504.
> >
> > The scheme has one impotant limitation. When several threads write to
> > single slot, this verifier may report false-positive result of missing
> > write barrier. But, I didn't see such situtations in any workloads I
> > have tested it with.
>
> The infrastructure based on the same idea, but independent of GC implementation
> is submitted as HARMONY-881. It provides patch for the VM, which incorporates
> the heap mirroring framework for write barrier verification into the VM core,
> and can work with any garbage collector.
>
>
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