At Mon, 21 Jan 2019 17:05:38 -0500 (EST), Mouse wrote: > > [...], mmap'ing audio device does not lead to improve any performance > > or latency. > > Then something is wrong. > > (a) It's the rare port on which copying to mmap()ped memory is no > faster than a user/kernel crossing plus a copyin.
I understand it. What I wanted to say is that mmap may be faster from such point of view but that difference may not make observable impact especially for application like audioplay(1). > Of course, if you're just playing a canned audio data stream and doing > nothing else, the latency issue doesn't matter; audioplay(1) is just such application. I want to keep it simple as possible. > Writing into an mmap()ped ring buffer takes advantage of the speed > differential and fixes the latency issue without requiring real-time > behaviour out of userland. Please let me confirm. Current audio mmap no longer points the hardware buffer. Is our understanding the same? Thanks. --- Tetsuya Isaki <is...@pastel-flower.jp / is...@netbsd.org>