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

[Helmut Eller]

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

Helmut

0001-WIP-create-pure-space-in-dump.patch
Description: Text Data