[Vm-dev] Re: [squeak-dev] Pinning GC

[Eliot Miranda]

On Wed, Apr 28, 2010 at 10:47 AM, John M McIntosh <
johnmci at smalltalkconsulting.com> wrote:

>
> Well to do pining you really need a separate oops space for fixed memory.
> You could ala 1984 macintosh HANDLES and slosh objects around the fixed
> ones, but that will lead to sand baring which was always a killer for them.
>

No, you don't.  Fixed space is an approach but is inflexible.  Instead a
pinning garbage collector does just that, pins objects as needed.  When it
moves objects to collect objects and/or compact memory, any pinned objects
are not moved, but other objects can be moved over them.  So the compactor
maintains a list of holes in to which to compact objects and moves objects
into the holes as they fit.  Between the holes are pinned objects.  The idea
is that objects are pinned only as long as they are accessible from FFI
callouts or an explicit pin set (for objects handed out to external code for
longer than the dynamic extent of a call).


> On 2010-04-28, at 10:24 AM, Eliot Miranda wrote:
>
> (moving to the vm list)
>
> On Tue, Apr 27, 2010 at 10:20 PM, Ang BeePeng <beepeng86 at yahoo.com> wrote:
>
>>
>> Hi all.
>>
>> Is pinning GC easy to do? Have anyone done that?
>>
>
> I'm not sure its easy, but I don't think it's particularly hard.  I think
> its certainly doable.  And it is something I very much want to do soon as it
> will make the threaded FFI Cog VM I've done much more scalable.  No, I've
> not even started on it yet.  But it will be part of the new object
> representation (much simpler class access) GC I also want to do.
>
> Sorry I don't yet have anything to show.
>
> best
> Eliot
>
>
>> Thanks.
>>
>> Ang Beepeng
>> --
>> View this message in context:
>> http://forum.world.st/Pinning-GC-tp2068628p2068628.html
>> Sent from the Squeak - Dev mailing list archive at Nabble.com.
>>
>>
>
> --
> ===========================================================================
> John M. McIntosh <johnmci at smalltalkconsulting.com>   Twitter:
>  squeaker68882
> Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
> ===========================================================================
>
>
>
>
>
>
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