[SOLVED] Need help on strange performance problem
From profiling my UE4.14.1 project, I am seeing ovr_SubmitFrame taking between 35 to 40ms in an empty scene. It appears to be related to the mirror to window operation because disabling mirror to window reduces ovr_SubmitFrame time down to 10ms which can be explained by VSync. Here is what I learned with a little bit of trial and error:
- Reducing the window swapchain size from 2048x2048 down to 640x480 does reduce ovr_SubmitFrame's time back down to 10ms.
- The drawcall for displaying the mirror texture only takes about 100us for the 2048x2048 backbuffer according to NSight.
- Doing sampling based profiling I am seeing ovr_SubmitFrame spending most of its time inside WaitForSingleObjectEx which suggest it is waiting at a sync point.
I have searched here as well as UDN and have found no info that can help me understand the observations I am seeing. If anybody can help me understand what I am seeing I would really appreciate it.
Jimmy
- Reducing the window swapchain size from 2048x2048 down to 640x480 does reduce ovr_SubmitFrame's time back down to 10ms.
- The drawcall for displaying the mirror texture only takes about 100us for the 2048x2048 backbuffer according to NSight.
- Doing sampling based profiling I am seeing ovr_SubmitFrame spending most of its time inside WaitForSingleObjectEx which suggest it is waiting at a sync point.
I have searched here as well as UDN and have found no info that can help me understand the observations I am seeing. If anybody can help me understand what I am seeing I would really appreciate it.
Jimmy