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From "Senaka Fernando" <senaka...@gmail.com>
Subject Re: Need info on copy-on-write support on Harmony
Date Sun, 06 Apr 2008 14:32:28 GMT
Hi Xiao-Feng, Alexei,

Thanks for the update. I'm not 100% aware of the usefulness of COW beyond
the scope of the Parrot VM, since this is a VM, the usefulness of COW would
depend on the upper layers that use it. Thus, perhaps when thinking about
uses of Parrot, and as we are interested in plugging the Harmony GC_Gen to
Parrot, we might need to support COW at least at an intermediate layer.

Most probably as it seems I believe that this can be handled in the
interfacing (porting) layer between Harmony and Parrot, which seems a bit
required in terms of interface aligning, as it seems. But, the approach
shouldn't need a 1-1 wrapper. This can rather be tailored to address
problems that may arise when aligning the interfaces.

Regards,
Senaka

On Sun, Apr 6, 2008 at 7:18 PM, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:

> Harmony GC doesn't have COW support (at the moment). COW can help to
> reduce the footprint when multiple processes are forked sharing data.
> It's not useful for Java (at the moment) because Java uses threads
> mostly.  Before we have real needs (workloads) for COW, we are not
> able to give an appropriate design.
>
> Thanks,
> xiaofeng
>
> On Sun, Apr 6, 2008 at 7:27 PM, Senaka Fernando <senakafdo@gmail.com>
> wrote:
> > Hi Alexei,
> >
> >  This issue came up when I was trying to match interfaces of Harmony
> GC_Gen
> >  and Parrot. It seems that the Parrot GC is aware on whether COW is
> used.
> >
> >  ex:- clear_cow, used_cow in dod.h
> >
> >  It seems that it maintains a COW ref count etc.
> >
> >  Regards,
> >  Senaka
> >
> >  On Sun, Apr 6, 2008 at 4:39 PM, Alexei Fedotov <
> alexei.fedotov@gmail.com>
> >  wrote:
> >
> >
> >
> >  > Hello Senaka,
> >  >
> >  > Copy-on-write semantics is used for native strings, see unistr.h If
> GC
> >  > would use copy-on-write, this would be rather implementation than
> >  > interface. Why do you need this info?
> >  >
> >  > Thanks.
> >  >
> >  > On Sun, Apr 6, 2008 at 12:36 PM, Senaka Fernando <senakafdo@gmail.com
> >
> >  > wrote:
> >  > > Hi all,
> >  > >
> >  > >  Need info on copy-on-write support on Harmony. I tried grepping
> the
> >  > source
> >  > >  but didn't uncover any related info. I also tried googling which
> was
> >  > not
> >  > >  that helpful. I would like to know whether Harmony has this
> feature?
> >  > and a
> >  > >  possible hint on where I should be looking would be really
> helpful.
> >  > >
> >  > >  Regards,
> >  > >  Senaka
> >  > >
> >  >
> >  >
> >  >
> >  > --
> >  > With best regards,
> >  > Alexei
> >  >
> >
>
>
>
> --
> http://xiao-feng.blogspot.com
>

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