3 ms·

> Wayland, being something relatively "new" compared to X11, has not had this level of scrutiny for as long. I'm looking forward to folks fixing it though. Par

> Wayland, being something relatively "new" compared to X11, has not had this level of scrutiny for as long. I'm looking forward to folks fixing it though. Part of the problem will doubtless be the USB (and Bluetooth) stacks including the device hardware and firmware. When keyboards and mice were serial devices with their own interrupt making the code path fast was achievable. I'm not so confident that modern peripheral stacks can be made to run with the same priority. It becomes even more challenging for devices sitting on a bus with multiple device classes or multiple protocols between the device and driver (USB -> Bluetooth -> Mouse). I hope devices can be sped up but we're a long way from a keypress triggering an interrupt and being handled in tens of milliseconds[0]. [0] https://danluu.com/input-lag/ https://danluu.com/input-lag/

ChuckMcM 2y ago
As a systems I guy I completely agree with this. One of the things that was interesting about X11 is that it draws an API "wall" around the stuff involved in presentation. Many folks don't remember this but we had X "terminals" which was a computer system that did nothing else except render the screen and handle the input. In that compartmentalization there was nothing else competing for attention. You didn't get USB bus contention because there was just the one mouse, ever, on the line between the user and the X11 server in the X terminal.
ndiddy 2y ago
The article you're commenting on is about someone running X11 and Wayland on the same computer with the same mouse and experiencing higher input latency on Wayland. I don't think differences between serial and USB mice are relevant here.
Permik 2y ago
USB devices today are dummy fast, USB 3.1 signals at 10 GHz. You just need to check the USB queue more often :D Alternatively you move straight up to USB 4, where we get pci-e interrupts again! :)
- hulitu 2y ago
  > USB devices today are dummy fast, In theory, yes. Not so, in practice. > USB 3.1 signals at 10 GHz. Yes but a mouse works at 12 MHz.

ChuckMcM 2y ago

As a systems I guy I completely agree with this. One of the things that was interesting about X11 is that it draws an API "wall" around the stuff involved in presentation. Many folks don't remember this but we had X "terminals" which was a computer system that did nothing else except render the screen and handle the input. In that compartmentalization there was nothing else competing for attention. You didn't get USB bus contention because there was just the one mouse, ever, on the line between the user and the X11 server in the X terminal.

ndiddy 2y ago

The article you're commenting on is about someone running X11 and Wayland on the same computer with the same mouse and experiencing higher input latency on Wayland. I don't think differences between serial and USB mice are relevant here.

Permik 2y ago

USB devices today are dummy fast, USB 3.1 signals at 10 GHz. You just need to check the USB queue more often :D Alternatively you move straight up to USB 4, where we get pci-e interrupts again! :)

hulitu 2y ago
> USB devices today are dummy fast, In theory, yes. Not so, in practice. > USB 3.1 signals at 10 GHz. Yes but a mouse works at 12 MHz.