Re: Merging scratch/no-purespace to remove unexec and purespace

[Helmut Eller <eller.helmut@gmail.com>]

On Tue, Dec 17 2024, Stefan Kangas wrote:

> Stefan Monnier <monnier@iro.umontreal.ca> writes:
[...]
>> That's because the pdump already fails to take advantage of the
>> purespace (i.e. the GC traces through the purespace like the rest of
>> the heap).
>
> I'll note that the best solution to that is to have a generational GC
> instead.  Simple, right?

A generational GC is definitely simpler.  Whether it's the "best"
solution is not so clear: A copying GC, like MPS, still needs to trace
and copy pure objects whenever the oldest generation is in the condemned
set.  Moving pure objects to a non-moving pool might be better.

> It's not entirely unrelated though: among other things, one reason why
> merging this would be good is that it would reportedly simplify the work
> on the igc branch.  And indeed any GC-related work now or in future.

Objects in purespace are immutable and immortal.  That's potentially
useful information for the GC.  Removing purespace also removes that
information.  Of course, if the pdumper already throws away this
information, then purespace just adds useless complexity.

Helmut