Re: AIO v2.5

Hi,

Attached is v2.10, with the following changes:

- committed core AIO infrastructure patch

A few cosmetic changes

- committed io_method=worker

Two non-cosmetic changes:

- The shmem allocation functions over-estimated the amount of shared memory
required.

- pgaio_worker_shmem_init() should initialize up to MAX_IO_WORKERS, not just
io_workers, since the latter is intentionally PGC_SIGHUP (found by Thomas)

- Bunch of typo fixes found by searching for repeated words

Thomas found one and then I searched for more.

- Added Melanie's patch to allow effective_io_concurrency to be set on windows etc

- Fixed a reference to an outdated function reference (thanks to Bilal)

- Reordered patches to be a bit more in dependency order

E.g. "bufmgr: Implement AIO read support" doesn't depend on Thomas' "buffer
forwarding" patches and thus can be commited before those go in.

Next steps:

- Decide what to do about the smgr interrupt issue

I guess it could be deferred, based on the argument it only matters with a
sufficiently high debug level, but I don't feel comfortable with that.

I think it'd be reasonable to just go with the patch I sent on the other
thread (and included here).

- Get somebody to look at
"bufmgr: Improve stats when buffer was read in concurrently"

This arguably fixes a bug, or just weird behaviour, on master.

- Address the set_max_safe_fds() issue and once resolved, commit io_uring
method

Can happen concurrently with next steps

- Commit "aio: Implement support for reads in smgr/md/fd"

- Get somebody to do one more pass at bufmgr related commits, I think they
could use a less in-the-weeds eye.

That's the following commits:
- localbuf: Track pincount in BufferDesc as well
- bufmgr: Implement AIO read support
- bufmgr: Use AIO in StartReadBuffers()
- aio: Basic read_stream adjustments for real AIO

Questions / Unresolved:

- Write support isn't going to land in 18, but there is a tiny bit of code
regarding writes in the code for bufmgr IO. I guess I could move that to a
later commit?

I'm inclined to leave it, the structure of the code only really makes
knowing that it's going to be shared between reads & writes.

- pg_aios view name

Greetings,

Andres Freund