Horton

Re: AIO v2.5

Andres Freund <andres@anarazel.de>

View thread
From: Andres Freund <andres@anarazel.de>
To: Antonin Houska <ah@cybertec.at>
Cc: Noah Misch <noah@leadboat.com>, pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Robert Haas <robertmhaas@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, Jelte Fennema-Nio <postgres@jeltef.nl>
Date: 2025-03-21T01:58:37Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. aio: Fix assertion, clarify README

  2. aio: Fix reference to outdated name

  3. aio: Fix possible state confusions due to interrupt processing

  4. aio: Improve debug logging around waiting for IOs

  5. aio: Fix crash potential for pg_aios views due to late state update

  6. Increase BAS_BULKREAD based on effective_io_concurrency

  7. localbuf: Add Valgrind buffer access instrumentation

  8. aio: Make AIO more compatible with valgrind

  9. aio: Avoid spurious coverity warning

  10. tests: Fix incompatibility of test_aio with *_FORCE_RELEASE

  11. tests: Cope with WARNINGs during failed CREATE DB on windows

  12. aio: Add errcontext for processing I/Os for another backend

  13. aio: Add README.md explaining higher level design

  14. aio: Minor comment improvements

  15. aio: Add test_aio module

  16. aio: Add pg_aios view

  17. docs: Add acronym and glossary entries for I/O and AIO

  18. Enable IO concurrency on all systems

  19. read_stream: Introduce and use optional batchmode support

  20. docs: Reframe track_io_timing related docs as wait time

  21. bufmgr: Use AIO in StartReadBuffers()

  22. bufmgr: Implement AIO read support

  23. aio: Add WARNING result status

  24. Let caller of PageIsVerified() control ignore_checksum_failure

  25. pgstat: Allow checksum errors to be reported in critical sections

  26. Add errhint_internal()

  27. localbuf: Track pincount in BufferDesc as well

  28. aio, bufmgr: Comment fixes/improvements

  29. Fix mis-attribution of checksum failure stats to the wrong database

  30. aio: Implement support for reads in smgr/md/fd

  31. aio: Add io_method=io_uring

  32. aio: Add liburing dependency

  33. aio: Rename pgaio_io_prep_* to pgaio_io_start_*

  34. aio: Pass result of local callbacks to ->report_return

  35. aio: Be more paranoid about interrupts

  36. Redefine max_files_per_process to control additionally opened files

  37. aio: Change prefix of PgAioResultStatus values to PGAIO_RS_

  38. bufmgr: Improve stats when a buffer is read in concurrently

  39. aio: Add io_method=worker

  40. aio: Infrastructure for io_method=worker

  41. aio: Add core asynchronous I/O infrastructure

  42. aio: Basic subsystem initialization

  43. tests: Expand temp table tests to some pin related matters

  44. localbuf: Introduce FlushLocalBuffer()

  45. localbuf: Introduce TerminateLocalBufferIO()

  46. localbuf: Fix dangerous coding pattern in GetLocalVictimBuffer()

  47. localbuf: Introduce StartLocalBufferIO()

  48. localbuf: Introduce InvalidateLocalBuffer()

  49. Allow lwlocks to be disowned

  50. Make jsonb casts to scalar types translate JSON null to SQL NULL.

  51. bufmgr/smgr: Don't cross segment boundaries in StartReadBuffers()

  52. Use aux process resource owner in walsender

  53. bufmgr: Return early in ScheduleBufferTagForWriteback() if fsync=off

Attachments

Hi,

Attached v2.11, with the following changes:


- Pushed the smgr interrupt change, as discussed on the dedicated thread


- Pushed "bufmgr: Improve stats when a buffer is read in concurrently"

  It was reviewed by Melanie and there didn't seem to be any reason to wait
  further.


- Addressed feedback from Melanie


- Addressed feedback from Noah


- Added a new commit: aio: Change prefix of PgAioResultStatus values to PGAIO_RS_

  As suggested/requested by Melanie. I think she's unfortunately right.


- Added a patch for some comment fixups for code that's either older or
  already pushed


- Added an error check for FileStartReadV() failing

  FileStartReadV() actually can fail, if the file can't be re-opened. I
  thought it'd be important for the error message to differ from the one
  that's issued for read actually failing, so I went with:

  "could not start reading blocks %u..%u in file \"%s\": %m"

  but I'm not sure how good that is.


- Added a new commit to redefine set_max_safe_fds() to not subtract
  already_open fds from max_files_per_process

  This prevents io_method=io_uring from failing when RLIMIT_NOFILE is high
  enough, but more than max_files_per_process io_uring instances need to be
  created.


- Improved error message if io_uring_queue_init() fails

  Added errhint()s for likely cases of failure.

  Added errcode().  I was tempted to use errcode_for_file_access(), but that
  doesn't support ENOSYS - perhaps I should add that instead?


- Disable io_uring method when using EXEC_BACKEND, they're not compatible

  I chose to do this with a define aio.h, but I guess we could also do it at
  configure time? That seems more complicated though - how would we even know
  that EXEC_BACKEND is used on non-windows?

  Not sure yet how to best disable testing io_uring in this case. We can't
  just query EXEC_BACKEND from pg_config.h unfortunately.  I guess making the
  initdb not fail and checking the error log would work, but that doesn't work
  nicely with Cluster.pm.


- Changed test_aio injection short-read injection point to zero out the rest
  of the IO, otherwise some tests fail to fail even if a bug in retries of
  partial reads is introduced


- Improved method_io_uring.c includes a bit (no pgstat.h)



Questions:


- We only "look" at BM_IO_ERROR for writes, isn't that somewhat weird?

  See AbortBufferIO(Buffer buffer)

  It doesn't really matter for the patchset, but it just strikes me as an oddity.



Greetings,

Andres Freund