On Tue, Jul 30, 2024 at 03:57:44PM +0800, Huan Yang wrote: > UDMA-BUF step: > 1. memfd_create > 2. open file(buffer/direct) > 3. udmabuf create > 4. mmap memfd > 5. read file into memfd vaddr Yeah this is really slow and the worst way to do it. You absolutely want to start _all_ the io before you start creating the dma-buf, ideally with everything running in parallel. But just starting the direct I/O with async and then creating the umdabuf should be a lot faster and avoid needlessly serialization operations. The other issue is that the mmap has some overhead, but might not be too bad. -Sima -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
