On Thu, Aug 13, 2015 at 12:30 AM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> Hi Ben,
>
> On Wed, Aug 12, 2015 at 8:46 AM, Ben Coman <btc at openinworld.com> wrote:
>>
>> On Wed, Aug 12, 2015 at 11:23 AM, Chris Muller <ma.chris.m at gmail.com>
>> wrote:
>> > In the 17 months since Squeak 4.5 was released, a huge development
>> > effort took place to create the next generation virtual-machine for
>> > the Squeak / Pharo / Newspeak family of programming systems.  Squeak
>> > is the modern incarnation of the Smalltalk-80 programming environment
>> > originally developed at the Xerox PARC.
>> >
>> > "Squeak 5" introduces this new VM and associated new memory model,
>> > collectively referred to as "Spur".  Presented [1] by Eliot Miranda
>> > and Clément Béra at the 2015 International Symposium on Memory
>> > Management, this new VM affords Squeak applications a significant
>> > boost in performance and memory management.  Among other
>> > optimizations, the #become operation no longer requires a memory scan.
>> > Object pinning and ephemerons are also now supported.  The release
>> > notes [2] provide more details.
>> >
>> > The new memory model requires a new image file format.  Although this
>> > new format results in about a 15% increased memory requirement for the
>> > same number of 4.x objects, a new segmented heap allows memory to be
>> > given back to the OS when its no longer needed, a great benefit for
>> > application servers.
>> >
>> > As forward compatibility is as important to the Squeak community as
>> > backward compatibility, Squeak 5 is delivers an image with identical
>> > content as the recent 4.6 release.  Although this new Squeak 5 VM
>> > cannot open images saved under the prior 4.x Cog format, objects and
>> > code can be easily exported from the 4.x image and then imported into
>> > Squeak 5.  Applications whose code runs strictly above the Smalltalk
>> > meta layer will prove remarkably compatible with the new format, most
>> > applications will require no changes whatsotever.
>> >
>> > Squeak 5 is the result of monumental effort by a tiny group of very
>> > talented people, but its also just the beginning of yet a new effort;
>> > Spur is just a stepping stone to a more ambitious goals planned over
>> > the next five years.
>>
>> > [1] -- A Partial Read Barrier for Efficient Support of Live
>> > Object-oriented Programming
>> >
>> > http://conf.researchr.org/event/ismm-2015/ismm-2015-papers-a-partial-read-barrier-for-efficient-support-of-live-object-oriented-programming
>> > [2] -- Squeak 5 Release Notes
>> > http://wiki.squeak.org/squeak/6207
>>
>> Congratulation guys.
>> Love figure 4 in the paper. Sub millisecond pause for garbage
>> collection of GB size images.
>
>
> Not on your life!  :-).  What we achieve is sub-millisecond pauses for
> become: in GB sized heaps.  But the point of Spur is that it *doesn't* do
> the compaction phase of a GC to implement become:, unlike  the standard VM.
> We do achieve millisecond pause times for scavenging (collecting the young
> generation) in large heaps, but that's no great shakes.  However, we do have
> plans to incrementalize global mark-sweep GC, and then the time taken will
> be amortized into pauses that should indeed be of the order of a
> millisecond.
>
>> cheers -ben
>
>
> _,,,^..^,,,_
> best, Eliot
>
>
>

Ahh, got it. I misread. Thanks for the correction.
cheers -ben