Frame rate drop caused by high polling rate mouse

[benkyoujouzu]

Bevy Version

0.13.1

System Information

SystemInfo { os: "Windows 11 Home", kernel: "22631", cpu: "AMD Ryzen 9 7940HS w/ Radeon 780M Graphics", core_count: "8", memory: "15.2 GiB" }

AdapterInfo { name: "NVIDIA GeForce RTX 4060 Laptop GPU", vendor: 4318, device: 10464, device_type: DiscreteGpu, driver: "NVIDIA", driver_info: "536.45", backend: Vulkan }

What Went Wrong

I have a mouse that allows me to adjust its polling rate. There are no issues when the mouse's polling rate is below 2000Hz. However, when I set the polling rate to 4000Hz, even in the simplest scenes, rapidly moving the mouse causes a significant drop in frame rate, with the maximum frame time increasing from around 10ms to about 80ms. Minimal example

1000Hz:

4000Hz:

What You Did

Since I haven't encountered similar issues in Godot and some games, it likely isn't a problem with the performance of my computer.

I tried using PresentMode::Fifo, PresentMode::Mailbox, and PresentMode::Immediate, but the frame drops did not improve.

I attempted the method from SDL#8756 using GetRawInputBuffer to acquire raw mouse input in a dedicated thread (my code), yet there was still no improvement.

Tracing data shows a lot of CursorMoved events between two frames when using a 4000Hz polling rate. I tried commenting out the code handling CursorMoved in bevy_winit and setting event_loop.listen_device_events(DeviceEvents::Never), but these did not solve the problem.

1000Hz:

4000Hz:

I suspect that some logic within bevy_winit or winit might be causing the stutter with high polling rate mice, but I haven't identified the cause. Do you have any idea?

[alice-i-cecile]

Are you able to reproduce this is in pure winit? Or in other front-ends that use winit, like eframe or I believe fyrox?

[benkyoujouzu]

Are you able to reproduce this is in pure winit? Or in other front-ends that use winit, like eframe or I believe fyrox?

I've tested the egui_demo_app and a demo in the fyrox tutorial, and both experience significant frame rate drops when using a high polling rate mouse. Therefore, it's likely that the problem lies within winit.

I found a winit issue that may be related to this problem: rust-windowing/winit#1418

[alice-i-cecile]

Awesome, that's very useful information. Thank you for investigating!

[benkyoujouzu]

I found the problem and made a pull request to winit rust-windowing/winit#3609.

Edit: This breaks some handling of winit. Additional fixes needed.

[AuracleTech]

I found the problem and made a pull request to winit rust-windowing/winit#3609.

Edit: This breaks some handling of winit. Additional fixes needed.

On my opened issue on winit I noted that I tested your pull but with no success, it made no difference between before / after the pull was added, if you have or want more information let me know.

Wanted to share this here because this is recent and seems highly relevant to this issue!

Note that I tried making a window with winit and with winapi directly, both had performance issues, so I suspect it's windows especially after my profiling results, so the only fix would be to find a workaround

[jf908]

After getting a high polling rate mouse recently, I investigated this issue a little bit and here's what I found:

1. I could replicate this on Windows even at 1000Hz polling rate (and setting it higher just makes it worse) with a bevy setup that shows fps and disable v-sync.
2. This doesn't appear to be an issue if you hide and lock the mouse cursor (FPS games rejoice).
3. This recent article talks about this issue with the Windows's input API and how it tackled the problem. I also read in a discussion of this article that solution 5 (making a new thread that does nothing but read events) is the industry standard solution but with so little literature on this niche topic, I couldn't find out any more.

The winit issue was closed but I wonder whether it's worth opening a new one seeing as it might be possible to improve performance using the technique from the article.