Horton

Re: AIO v2.0

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: pgsql-hackers@postgresql.org
Date: 2024-09-03T14:29:07Z
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 aio: Fix reference to outdated name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

Hi,

On 2024-09-02 13:03:07 +0300, Heikki Linnakangas wrote:
> On 01/09/2024 09:27, Andres Freund wrote:
> > In the next few days I'll add a bunch more documentation and comments as well
> > as some better perf numbers (assuming my workstation survived...).
> 
> Yeah, a high-level README would be nice. Without that, it's hard to follow
> what "handed out" and "defined" above means for example.

Yea - I had actually written a bunch of that before, but then redesigns just
obsoleted most of it :(

FWIW, "handed out" is an IO handle acquired by code, which doesn't yet have an
operation associated with it. Once "defined" it actually could be - but isn't
yet - executed.


> A few quick comments the patches:
> 
> v2.0-0001-bufmgr-Return-early-in-ScheduleBufferTagForWrit.patch
> 
> +1, this seems ready to be committed right away.

Cool


> v2.0-0002-Allow-lwlocks-to-be-unowned.patch
> 
> With LOCK_DEBUG, LWLock->owner will point to the backend that acquired the
> lock, but it doesn't own it anymore. That's reasonable, but maybe add a
> boolean to the LWLock to mark whether the lock is currently owned or not.

Hm, not sure it's worth doing that...


> The LWLockReleaseOwnership() name is a bit confusing together with
> LWLockReleaseUnowned() and LWLockrelease(). From the names, you might think
> that they all release the lock, but LWLockReleaseOwnership() just
> disassociates it from the current process. Rename it to LWLockDisown()
> perhaps.

Yea, that makes sense.


> v2.0-0008-aio-Skeleton-IO-worker-infrastructure.patch
> 
> My refactoring around postmaster.c child process handling will conflict with
> this [1]. Not in any fundamental way, but can I ask you to review those
> patch, please? After those patches, AIO workers should also have PMChild
> slots (formerly known as Backend structs).

I'll try to do that soonish!

Greetings,

Andres Freund