[squeak-dev] Segmented object memory (was: Can I create a 75 Gb Image?)

David T. Lewis lewis at mail.msen.com
Mon Oct 18 22:50:07 UTC 2021

On Mon, Oct 18, 2021 at 05:14:44PM +0200, Marcel Taeumel wrote:
> Hi Timothy --
> I am not aware of basic support for automatic paging/swapping of the
> object space in the OSVM. Wouldn't the GC become more challenging to
> implement, too? Yet, I recall that there has been some PhD work on that
> topic ... probably using a pre-Spur VM ... Well, you can use
> (Native)ImageSegment (primitives 98 and 99) to manually manage part of
> the object space, right?
Interesting that you mention it. I recall reading an announcement
from Dan Ingalls on the early squeak-dev mailing list in which he
described his image segments design (https://wiki.squeak.org/squeak/2316).
At the time, I assumed that this was intended as a mechanism for supporting
large object memories on machines with limited physical memory. Segmented
memory spaces were of course a very common strategy, as anyone with
experience with 16-bit systems will know. But my assumption was probably
wrong. ImageSegment has been used for lots of interesting things but never 
(as far as I know) for implementing a segmented ObjectMemory in Squeak.

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