> Date: Tue, 03 Sep 2024 16:36:44 +0100
> From: "Stephane Travostino" <s...@combo.cc>
> Cc: 72...@debbugs.gnu.org
>
> > Please try profiling the lagging cases with "M-x profiler", and post
> > the profile here.
>
> I don't know how to make a consistent test case. I have tried here to profile
> opening Emacs (same commit with and without PGTK) on the same 547-line Elixir
> file, and holding the Down key until it reaches the bottom and then back to
> the top of the buffer. I have (setopt scroll-conservatively 101) so after the
> first page the contents are continuously redrawn for every new line.
>
> The PGTK version feels like it's skipping frames while it's relatively smooth
> on X11:
>
> X11:
> 8795 86% + redisplay_internal (C function)
> 1141 11% + command-execute
> 54 0% + direnv--maybe-update-environment
> 49 0% + gcmh-register-idle-gc
> 42 0% + winner-save-old-configurations
> 20 0% + timer-event-handler
> 18 0% + ...
> 18 0% + jit-lock--antiblink-post-command
>
>
> PGTK:
> 9387 91% + redisplay_internal (C function)
> 698 6% + command-execute
> 19 0% + ...
> 19 0% + timer-event-handler
> 12 0% + direnv--maybe-update-environment
> 11 0% + winner-save-old-configurations
>
> I have run this a few times and in Wayland `redisplay_internal` takes always
> a few percent more time than on X11, though I am not sure these numbers can
> prove anything as they are quite close.
Thanks. Maybe Po Lu will have some ideas.
> Is there some kind of consistent UI benchmark I can run? The frame skipping
> reminds me of missed vsync deadlines one might experience in games.
Try this:
(defun scroll-up-benchmark ()
(interactive)
(let ((oldgc gcs-done)
(oldtime (float-time)))
(condition-case nil (while t (scroll-up) (redisplay))
(error (message "GCs: %d Elapsed time: %f seconds"
(- gcs-done oldgc) (- (float-time) oldtime))))))
Evaluate this function, then visit a large file, like src/xdisp.c from
the Emacs sources, and invoke "M-x scroll-up-benchmark RET". It will
show the time it took at the end. Record the results and compare with
the other configuration.
