Horton

Re: AIO v2.5

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: pgsql-hackers@postgresql.org
Cc: Thomas Munro <thomas.munro@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Noah Misch <noah@leadboat.com>, Robert Haas <robertmhaas@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>
Date: 2025-03-10T18:23:12Z
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 aio: Fix reference to outdated name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 is v2.6 of the AIO patchset.

Relative to 2.5 I:

- Improved the split between subsystem initialization and main AIO commit, as
  well as the one between worker infrastructure and io_method=worker

  Seemed worth as the only one voicing an opinion about squashing those
  commits was opposed.


- Added a lot more comments to aio.h/aio_internal.h. I think just about
  anything that should conceivably have a comment has one.


- Reordered fields in PgAioHandle to waste less due to padding


- Narrowed a few *count fields, they were 64bit without ever being al to reach
  that


- Used aio_types.h more widely, instead of "manual" forward declarations. This
  required moving a few typedefs to aio_types.h


- Substantial commit message improvements.


- Removed the pg_aios.error_desc column, due to:
  https://postgr.es/m/qzxq6mqqozctlfcg2kg5744gmyubicvuehnp4a7up472thlvz2%40y5xqgd5wcwhw


- Reordered the commits slightly, to put the README just after the
  smgr.c/md.c/... support, as the readme references those in the examples


- Stopped creating backend-local io_uring instances, that is vestigial for
  now. We likely will want to reintroduce them at some point (e.g. for network
  IO), but we can do that at that time.


- There were a lot of duplicated codepaths in bufmgr.c support for AIO due to
  temp tables. I added a few commits refactoring the temp buffers state
  management to look a lot more like the shared buffer code.

  I'm not sure that that's the best path, but they all seemed substantial
  improvements on their own.


- putting io_method in PG_TEST_INITDB_EXTRA_OPTS previously broke a test,
  because Cluster::init() puts PG_TEST_INITDB_EXTRA_OPTS after the # options
  specified by ->extra. I now worked around that by appending the io method to
  a local PG_TEST_INITDB_EXTRA_OPTS, but brrr.


- The tracepoint for read completion omitted the fact that it was a temp
  table, if so.


- Fixed some duplicated function decls, due to a misresolved merge-conflict


Current state:

- 0001, 0002 - core AIO - IMO pretty much ready

- 0003, 0004 - IO worker - same

- 0005, 0006 - io_uring support - close, but we need to do something about
  set_max_fds(), which errors out spuriously in some cases

- 0007 - smgr/md/fd.c readv support - seems quite close, but might benefit from
  another pass through

- 0008 - README - I think it's good, but I'm probably not seeing the trees for
  the forest anymore

- 0009 - pg_aios view - naming not resolved, docs missing

- 0010 to 0014 - from another thread, just included here due to a dependency

- 0016 to 0020 - cleanups for temp buffers code - I just wrote these to clean
  up the code before making larger changes, needs review

- 0021 - keep BufferDesc refcount up2date for temp buffers - I think that's
  pretty much ready, but depends on earlier patches

- 0022 - bufmgr readv AIO suppot - some naming, some code duplication needs to
  be resolved, but otherwise quite close

- 0023 - use AIO in StartReadBuffers() - perhaps a bit of polishing needed

- 0024 - adjust read_stream.c for AIO - I think Thomas has a better patch for
  this in the works

- 0025 - tests for AIO - I think it's reasonable, unless somebody objects to
  exporting a few bufmgr.c functions to the test

- the rest: Not for 18

Greetings,

Andres Freund