On Thu, Jul 13, 2023 at 6:50 AM Dimitrios Apostolou <jimis@xxxxxxx> wrote: > Interesting and kind of sad that the last update on the wiki page is from > 2021. What is the latest prototype? I'm not sure I'm up to the task of > putting my database to the test. ;-) It works pretty well, certainly well enough to try out, and work is happening. I'll try to update the wiki with some more up-to-date information soon. Basically, compare these two slides (you could also look at slide 11, which is the most most people are probably interested in, but then you can't really see what's going on with system call-level tools): https://speakerdeck.com/macdice/aio-and-dio-for-postgresql-on-freebsd?slide=7 https://speakerdeck.com/macdice/aio-and-dio-for-postgresql-on-freebsd?slide=9 Not only are the IOs converted into 128KB preadv() calls, they are issued concurrently and ahead of time while your backend is chewing on the last lot of pages. So even if your file system completely fails at prefetching, we'd have a fighting chance at getting closer to device/line speed. That's basically what you have to do to support direct I/O, where there is no system-provided prefetching.
