[Bug 105695] [PERF] Updating ubo offset via vkCmdBindDescriptorSets is causing flush that is taking 50% of rendering time

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Thu Mar 29 14:55:51 UTC 2018


Vyacheslav <ytriffy at gmail.com> changed:

           What    |Removed                     |Added
             Status|NEEDINFO                    |RESOLVED
         Resolution|---                         |NOTABUG

--- Comment #4 from Vyacheslav <ytriffy at gmail.com> ---
I found the problem with my code - I did vkQueueWaitIdle() after each frame and
it was taking up 80% of rendering time (yes, I'm still learning vulkan). I
changed it to waiting on fences that are passed to vkQueueSubmit(). I have
triple buffering, so I have three images in swap chain - 0,1,2. I record
command buffers, submit and present 0,1,2 without waiting, then on frame 3 I
wait on fence for completion of rendering of frame 0. On frame 4 I wait for
completion of frame 1 and so on. I know I can do more than 3 but that alone
gave me a big performance increase. Now in vulkan I get 28ms/frame, in opengl
58ms/frame. And on vulkan cpu is load is <70%, in opengl cpu load is constantly
>95%. So lesson learned - proper synchronization is important.

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