5 ms·

Ubuntu latency is better than Windows 10 on this hardware?! Way to go! Better check your videocard driver's settings. For NVidia on Windows, you can for exampl

by stinos 10y ago

Ubuntu latency is better than Windows 10 on this hardware?! Way to go! Better check your videocard driver's settings. For NVidia on Windows, you can for example alter number of prerendered frames which IIRC defaults to at least 3. Putting that to 0 and turning off a bunch of other things listed in the settings, decent nVidia cards on decent hardware can get a latency of 2 frames which is probably the bare minimum. At 60Hz with a screen which doesn't add additional latency that is 33.3mSec (between the software issueing a render call and the actual output on the screen). At work we measure latency using an oscilloscope, a photodiode pointed to the (top left of the) screen and some input event e.g. from a fast digital output card (i.e. less than a mSec to get an output high from software). E.g. in software we set an output high in the piece of code of interest then just measure the time between that high edge and the photodiode firing. But using a camera is a neat though somewhat more manual process.

swinglock 10y ago
On the Windows 10 performance, I did a single test and found something mildly interesting. I tested in Notepad and have the "Hide pointer while typing" setting enabled, and found the first thing that happens on screen is the pointing becoming hidden. That happens after 50 ms. The character shows up in Notepad 16.7 ms later. This was measured with a 120 FPS camera and an old 60 Hz monitor.
- jesperhh 10y ago
  This is likely because the gpu has specific hardware for drawing the cursor on top of the current framebuffer, which can be turned off quicker than the character can be drawn to the framebuffer
  - swinglock 10y ago
    Indeed it does. When using f.lux the color temperature of the cursor remains unchanged due to this.
    - kevingadd 10y ago
      You can also observe it in many cases while dragging a window - the composited window's position will lag behind the position of the cursor.
kevingadd 10y ago
DWM also adds at least one frame of latency (usually two I think?) at all times. If you bypass composition (through exclusive mode fullscreen) that additional compositor latency goes away. Higher refresh rate would also drop that latency, naturally.

by stinos 10y ago

swinglock 10y ago

On the Windows 10 performance, I did a single test and found something mildly interesting. I tested in Notepad and have the "Hide pointer while typing" setting enabled, and found the first thing that happens on screen is the pointing becoming hidden. That happens after 50 ms. The character shows up in Notepad 16.7 ms later. This was measured with a 120 FPS camera and an old 60 Hz monitor.

jesperhh 10y ago
This is likely because the gpu has specific hardware for drawing the cursor on top of the current framebuffer, which can be turned off quicker than the character can be drawn to the framebuffer
- swinglock 10y ago
  Indeed it does. When using f.lux the color temperature of the cursor remains unchanged due to this.
  - kevingadd 10y ago
    You can also observe it in many cases while dragging a window - the composited window's position will lag behind the position of the cursor.

kevingadd 10y ago

DWM also adds at least one frame of latency (usually two I think?) at all times. If you bypass composition (through exclusive mode fullscreen) that additional compositor latency goes away. Higher refresh rate would also drop that latency, naturally.