How to know the exact number of queued frames when using wgpu::PresentMode::Fifo mode?

[archee565]

The number of queued frames are either 2 or 3 on my test systems.

I would call game physics update while the GPU is taking long on a frame, by polling with device.poll(wgpu::PollType::Wait ...) I would normally poll the frame before last frame, if 3 frames can be queued, so that there would be no GPU idle while another frame is being submitted.

Do you recommend a separate thread for game update loop instead of the polling method?