Horton

Re: SLRU optimization - configurable buffer pool and partitioning the SLRU lock

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: tender wang <tndrwang@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-01-31T23:31:34Z
Lists: pgsql-hackers

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On 2024-Jan-29, Dilip Kumar wrote:

> Thank you for working on this.  There is one thing that I feel is
> problematic.  We have kept the allowed values for these GUCs to be in
> multiple of SLRU_BANK_SIZE i.e. 16 and that's the reason the min
> values were changed to 16 but in this refactoring patch for some of
> the buffers you have changed that to 8 so I think that's not good.

Oh, absolutely, you're right.  Restored the minimum to 16.

So, here's the patchset as two pieces.  0001 converts
SlruSharedData->latest_page_number to use atomics.  I don't see any
reason to mix this in with the rest of the patch, and though it likely
won't have any performance advantage by itself (since the lock
acquisition is pretty much the same), it seems better to get it in ahead
of the rest -- I think that simplifies matters for the second patch,
which is large enough.

So, 0002 introduces the rest of the feature.  I removed use of banklocks
in a different amount as banks, and I made commit_ts use a longer
lwlock acquisition at truncation time, rather than forcing all-lwlock
acquisition.

The more I look at 0002, the more I notice that some comments need badly
updated, so please don't read too much into it yet.  But I wanted to
post it anyway for archives and cfbot purposes.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/

Commits

  1. Fix zeroing of pg_serial page without SLRU bank lock

  2. Fix misspelled assertions

  3. GUC table: Add description to computed variables

  4. Improve performance of subsystems on top of SLRU

  5. Rename SLRU elements in view pg_stat_slru

  6. Use atomic access for SlruShared->latest_page_number

  7. Split use of SerialSLRULock, creating SerialControlLock

  8. Index SLRUs by 64-bit integers rather than by 32-bit integers

  9. Add a macro templatized hashtable.