On Tue, Jul 30, 2024 at 08:04:04PM +0800, Huan Yang wrote: > > 在 2024/7/30 17:05, Huan Yang 写道: > > > > 在 2024/7/30 16:56, Daniel Vetter 写道: > > > [????????? daniel.vetter@xxxxxxxx ????????? > > > https://aka.ms/LearnAboutSenderIdentification?????????????] > > > > > > 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 > > That's greate, Let me rephrase that, and please correct me if I'm wrong. > > > > UDMA-BUF step: > > 1. memfd_create > > 2. mmap memfd > > 3. open file(buffer/direct) > > 4. start thread to async read > > 3. udmabuf create > > > > With this, can improve > > I just test with it. Step is: > > UDMA-BUF step: > 1. memfd_create > 2. mmap memfd > 3. open file(buffer/direct) > 4. start thread to async read > 5. udmabuf create > > 6 . join wait > > 3G file read all step cost 1,527,103,431ns, it's greate. Ok that's almost the throughput of your patch set, which I think is close enough. The remaining difference is probably just the mmap overhead, not sure whether/how we can do direct i/o to an fd directly ... in principle it's possible for any file that uses the standard pagecache. -Sima -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
