On 8/25/23 12:12, Giuseppe D'Angelo via Development wrote:
On 24/08/2023 21:37, Eduardo Hopperdietzel wrote:
The results show that there's no significant difference in the time
it takes for read and write operations using QPainter in SHM and DMA
maps.
I'm really curious here, and these aren't rhetorical questions: why
would anyone expect to be a difference in performance, as far as
QPainter is concerned? Isn't it ultimately just using a CPU-based
renderer onto a block of memory? Why should it make a difference where
that memory comes from / how it's managed / etc.? Are we're talking
about "far memory" (NUMA-like) scenarios?
It makes a difference to the compositor. The compositor will have to
upload pixel data from RAM to VRAM so it can composite the windows using
OpenGL or Vulkan. If the client provides dmabuf client buffers, the
compositor can skip the uploading step thus reduce the amount of time it
takes to compose a frame.
Regards,
Vlad
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