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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [DRLVM][GC] parallel compaction and wasted virtual space
Date Mon, 30 Oct 2006 01:50:15 GMT
This is a good idea, Ivan :-) We need implement at least a fall back
parallel algorithm for Compressor in case its required vitual space is
not enough.

Thanks,
xiaofeng

On 10/29/06, Ivan Volosyuk <ivan.volosyuk@gmail.com> wrote:
> Excellent algorithm. I think it makes sense to implement it. If we
> can't use on 32 bit machines with plenty of ram, we can use it on 64
> bit machines.
> What about enabling the algorithm at runtime if required conditions
> are met, otherwise falling back to some other algorithm?
> --
> Ivan
>
> On 10/28/06, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:
> > Hi, all, the plan for GCv5 parallel compaction is to apply the idea of
> > Compressor [1]. But it has an issue I want to discuss with you.
> > Compressor needs to reserve an unmapped virtual space for compaction.
> > The size of the reserved part is the same as that of copy reserve
> > space in a semi-space collector. This means about that part of the
> > virtual space is unusable for the JVM. In a typical setting, the
> > wasted part is half size of the total compaction space. If we have 1GB
> > physical memory, the JVM is ok for Compressor because the virtual
> > space is large enough to wast half; but if the phsical memory is >2GB,
> > Compressor may have a problem in 32bit machine: some of phsical mapped
> > space might be wasted.
> >
> > Any opinion on this?
> >
> > Thanks,
> > xiaofeng
> >
> > [1] http://www.cs.technion.ac.il/~erez/Papers/compressor-pldi.pdf
> >
>
>
> --
> Ivan
> Intel Enterprise Solutions Software Division
>

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