2 ms·
As I understand it: - Compositing is done on the GPU - BitBlt is done on the CPU - Copies from GPU -> CPU are slow So, yeah, compositing adds a frame of VSy
by mastax 9y ago
As I understand it:
- Compositing is done on the GPU
- BitBlt is done on the CPU
- Copies from GPU -> CPU are slow
So, yeah, compositing adds a frame of VSync latency, but these measurements are complete bunkum.
- leeter 9y agoBitBlt is done in DMA ram by the CPU, so it may be even worse than just a copy as there is likely a wait involved too to prevent shared access. Using DMA ram prohibits the GPU/Driver from doing optimizations on that ram that it could do if the buffer was in dedicated gpu-ram. This is why DX12 resources are generally always copied into non-shared buffers.