Re: macOS metal rendering engine in mac port

[Aaron Jensen]

On Sat, May 22, 2021 at 11:45 AM Alan Third <alan@idiocy.org> wrote:
>
> On my machine the scroll benchmark shows Emacs 27 being able to update
> the screen more than twice as fast as any version of the Mac port, yet
> this shows Emacs 27 isn't really any better.

For some reason, Emacs Mac port (non-metal) doesn't paint the screen
during scroll-up-benchmark, it just pauses, but it's faster on my
machine.

Full screen frame, with line numbers (11k lines):

Mac port: 2.88s
emacs27-drawing branch: 4.42s
master: 6.75s

Full screen frame, no line numbers (11k lines):

Mac port 2.24s
emacs27-drawing branch: 3.13s
master: 5.3s

>
> Perhaps they both reach the maximum input rate?
>
> Or the NS port's event handling is slow, which is quite possible as
> it's single threaded and I think the Mac port uses a separate thread
> for toolkit stuff. (Someone please correct me if I'm wrong.)

Ah that might explain why things feel a little faster, especially w/
company-mode.

> IIRC you said that you still thought input in Emacs 27 feels sluggish?
>
> > I've attached a couple profiles of the surface stuff branch.
>
> It turns out I can't open these because my version of xcode is too
> old... Although I think it's the most recent I can use on this
> machine.

Doh. I'll send screenshots next time.

> > Of note is that display-line-number-mode seems to be a massive
> > culprit in slowing this down. Turning that off about gives me about
> > 50% more performance.
>
> Does it give a similar slowdown in the Mac port?

Not quite as significant. And on the scrolling benchmark, it's not
50%, but it is 25-40%

> > The rest of what takes time appears to be mem copies, which makes
> > sense that that would scale w/ screen size.
>
> If someone wanted to send me a 5k screen, debugging this would be a
> lot easier. ;)

I may be selling mine in time... Is it possible to set your resolution
to higher than your monitor supports and scale it down? Also, maybe
decreasing your font size may change things as there'd be more lines.

Aaron