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

[Stefan Kangas <stefankangas@gmail.com>]

Helmut Eller <eller.helmut@gmail.com> writes:

> On Wed, Dec 18 2024, Helmut Eller wrote:
>
> [...]
>> So the pdumper copies objects from purespace to the dump like normal
>> objects; when loading the dump, purespace stays empty.
>>
>> I had (wrongly) assumed that the pdumper creates a separate section for
>> pure objects.  Creating such a section sounds easy enough (hmm, maybe
>> not so easy because of hashtables).  Still not sure if it would be worth
>> the effort.
>
> Out of curiosity, I implemented such a section with the attached patch.
> It seems that it would save ~2ms per collection cycle.
>
> To measure this, I compared the output of
>
>  ./src/emacs -Q --batch --eval \
>  '(let* ((stats (benchmark-run 1000 (garbage-collect))))
>      (message "%s" (/ (elt stats 2) (elt stats 1))))'
>
> between the versions with and without the patch.  The results was:
>
>    without-pure-section: 0.006251480181
>       with-pure-section: 0.003986384857

This is interesting, thanks.  Would this experiment easily transfer to
and be relevant to the MPS branch?