MrShoor's input lag investigation and solution

[SilverWarior]

I don't speak Russian so I'm not able to read the contents of that article but after playing a little bit with this test executable I'm noticing several problems which contradicts with your explanation of the article:

1. When I run test application and have GPU load slider all the way to the left (the least GPU load) it is reaching 147 FPS. This means that there is no Vsync enabled. I have 60 Hz LCD monitor which means that there shouldn't be more than 60 FPS.
   Also while the GPU load slider is set to minimum test application is maxing out the main thread. So in case of real game this would cause lag on all CPU processing tasks, like physics for instance.
2. If I do as you ask and increase GPU load so that FPS drops down to around 20 I can notice considerable lag when rotating the cube without any lag reduction method selected. The load of the main thread now drops down to about 3.54 % of entire CPU load (approximately 25 % load of single CPU core).
   Lag becomes much less noticeable if I select any of the lag reduction methods. But if I chose lag reduction method "Query event" test application again maxes out the main thread entirely. Other two methods doesn't seem to have much effect on CPU usage.
3. But if I set the GPU load so that test application is reaching 60 FPS I barely notice any or no lag even when no lag reduction method is selected. GPU at this time is at 100% load.
   If I select "SetMaximumLatencyFrame(1)" lag prevention method I don't notice any difference. My GPU usage still stays at roughly 100%.
   If I select "Query Event" lag prevention method I actually notice slight lag probably because test application is again maxing out its main thread. I also see slight decrease in GPU usage of about 4%. I suspect this might be caused because of CPU bottlenecking in this case.
   And if I select "GenerateMips" lag prevention method again I don't notice any lag. And now my GPU load has dropped for about 6% and CPU load stay around 3.5%
4. And if I max out the GPU load there is a huge lag as expected In fact the lag becomes so big that the whole Windows UI starts lagging not just the test application.
   But what seems strange to me is that even with max GPU load choosing "Query event" lag prevention method still maxes out the main thread of the test application. So using this lag prevention method is probably not a god solution due to high CPU loads all the time.

Now how can I test this with Vsync enabled? I don't want to force Vsync for this test application using my graphics drivers since they might affect the results in unexpected ways (not sure if forcing Vsync through drivers only enables Vsync or does something more).

PS: My computer specs are:
AND FX 8350 Eight Core CPU running at 4 GHz
Radeon R9 270 GPU runing at 975 MHz
My computer is running Windows 7 64 Bit

[Chebmaster]

Now how can I test this with Vsync enabled?

No idea, sorry. This thing uses Direct3d 11 but I have ever only studied OpenGL.

is reaching 147 FPS. This means that there is no Vsync enabled

Huh, I haven't noticed because it only reaches 39 fps on my laptop (and dies if I move the slider more than a tiniest silver to the right).

But if I chose lag reduction method "Query event" test application again maxes out the main thread entirely.

Hmm, system dependent, then. No such thing @ Win7 64 + i5 2450M + HD 3000.

Only the mipmap method is available for OpenGL anyway.

[de_jean_7777]

Under heavy load, the input lag is visibly reduced on a win 10 machine. Might eventually implement something like this for myself.