Re: Improve configurability for IO related behavoir

On Sun, May 29, 2022 at 4:29 AM 浩辰 何 <hehaochen(at)hotmail(dot)com> wrote:
> Furthermore, the results above are also related to IO API supported by OS. MySQL support synchronized IO and Linux libaio. It seems
> that PostgreSQL only supports synchronized IO, so shall we support more IO engines? like io_uring which is very popular in recent years.

Hi Haochen,

There is an active project to bring these things to PostgreSQL.
https://wiki.postgresql.org/wiki/AIO has some information and links.
The short version is that there is a development patch set to add
these GUCs:

io_method=worker,io_uring,posix_aio,iocp,...
io_data_direct=on,off
io_wal_direct=on,off

It also adds a bunch of specialised logic that knows how to initiate
IO in key places (scans, writeback, recovery, ...), because it's not
enough to just turn off kernel I/O buffering, we also have to do all
the work the kernel is doing for us or performance will be terrible.