FPS noticeably slows down from Direct3D11 to Direct3D12

[cloudwu]

When I change renderer from d3d11 to d3d12 , the examples noticeably slows down when vsync is off.

NVIDIA GeForce GTX 1050 Ti , Example 1

Direct3D 12.5 : FPS 900 FPS Render wait : 1.9 ms
Direct3D 11.3 : FPS 17000 FPS Render wait : 0.1 ms

Why Render wait time is much longer in d3d12 ?

[bkaradzic]

Uncomment line with D3D11_CREATE_DEVICE_PREVENT_INTERNAL_THREADING_OPTIMIZATIONS when comparing:

bgfx/src/renderer_d3d11.cpp

Line 892 in 79d1b4d

// | D3D11_CREATE_DEVICE_PREVENT_INTERNAL_THREADING_OPTIMIZATIONS

[cloudwu]

I tried to uncomment D3D11_CREATE_DEVICE_PREVENT_INTERNAL_THREADING_OPTIMIZATIONS today.

The average Render wait in D3D11 is 0.15 ms, and about 1.9 ms in D3D12 .

ps.

16ms in D3D9 (it seems that it can't turn off vsync in D3D9.)
0.3ms in OpenGL 2.1

[cloudwu]

I run it on another computer with GTX 3060 Ti, It's slower .

D3D12 Render wait > 3ms