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Desktop compositing latency is real

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Re: Desktop compositing latency is real

#41

Post by pjc50 »

83457 wrote: post #33
nickjj wrote: post #23

This is also why picking a good monitor is important for software development. Some monitors have tons of input lag (60-70ms) and that's the time it takes for you to see what you're typing to reach the display. This also includes the time it takes to see you move your mouse cursor too. I did a huge write up on picking a good monitor for development which can be found at: https://nickjanetakis.com/blog/how-to-pick-a-g…

"I can send an IP packet to Europe faster than I can send a pixel to the screen. How f’d up is that?" - John Carmack

Solution: send the pixel to the screen over IP!

(joking, but with a tiny serious element)

Re: Desktop compositing latency is real

#42

Post by amiga-workbench »

Zardoz84 wrote: post #31

> Don’t you find it a bit funny that Windows 95 is actually snappier than Windows 10? It’s really a shame that response times in modern computers are visibly worse than those in twenty years ago. My Amiga A1200 (Only have extra RAM) feels faster and more responsive that any modern computer with Windows or GNU/Linux desktop.

I was seriously impressed with how well BeOS performed too.

I've got a Blizzard 1230-IV with 128mb of RAM bunged into my A1200 at the moment and it runs rings around my desktop running Gnome.

Re: Desktop compositing latency is real

#43

Post by forgotmypw »

Someone recently gave me an old PowerBook G3, running Mac OS 8.6. I was amazed by how responsive the UI is compared to today's UIs, from Mac to Windows to iOS to Android. When I clicked something, it felt like there was a pushrod between the mouse button and the menu, which triggered it instantly.

Re: Desktop compositing latency is real

#45

Post by em3rgent0rdr »

Zardoz84 wrote: post #31

> Don’t you find it a bit funny that Windows 95 is actually snappier than Windows 10? It’s really a shame that response times in modern computers are visibly worse than those in twenty years ago. My Amiga A1200 (Only have extra RAM) feels faster and more responsive that any modern computer with Windows or GNU/Linux desktop.

> "or GNU/Linux desktop"

I believe Wayland has made some latency improvements.

Re: Desktop compositing latency is real

#48

Post by em3rgent0rdr »

pjc50 wrote: post #41
83457 wrote: post #33

Earlier quoted context omitted.

"I can send an IP packet to Europe faster than I can send a pixel to the screen. How f’d up is that?" - John Carmack

Solution: send the pixel to the screen over IP! (joking, but with a tiny serious element)

this reminds me of the argument that instead of going to USB C 3.1 as the grand unifying connector for all peripherals (including video), we should have instead migrated to Ethernet cables for everything.

Re: Desktop compositing latency is real

#49

Post by floatboth »

vetinari wrote: post #20
ahartmetz wrote: post #7

I recently measured it with my phone's camera in slow motion mode. The system is an AMD Ryzen 1800X with AMD R9 280x GPU, KDE Plasma with KWin window manager in compositing mode. Key press to screen output latency was ~33 millseconds (90 fps recording, so increments of 11) in KWrite. The computer feels plenty responsive with that latency, and I hate latency... It is a full stack real world result - for comparison pur…

33 ms is two frames, if your monitor is at 60 Hz. If you tried vscode or other electron app, it might be 49 ms (3 frames). These are the numbers I'm getting from 1900X with Nvidia 1080 GPU, Gnome3, 4k@60hz, but without measuring latency of the keyboard itself. Modern keyboards are another part of the problem. They can also take their sweet time since keypress until packet appears at the USB bus. See https://danluu.co…

Modern motherboards often still have a PS/2 port! And most USB keyboards still support PS/2, a passive adapter works great.

Re: Desktop compositing latency is real

#50

Post by lukeschlather »

srcmap wrote: post #35

According to this: https://www.youtube.com/watch?v=BTURkjYJ_uk Firefox's servo engine can compose CSS elements/Display List together at 500 frames / second. Maybe next version of Windows / Linux desktop should use FF's servo engine?

That's throughput, though, not latency. I would guess that servo's input latency is significantly more than 2ms, even if their throughput for certain rendering operations is 500 fps.
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