Horton

Re: Reducing the chunk header sizes on all memory context types

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Julien Rouhaud <rjuju123@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2022-10-19T18:55:03Z
Lists: pgsql-hackers 
Hi,

On 2022-10-11 10:21:17 +0700, John Naylor wrote:
> On Tue, Oct 11, 2022 at 5:31 AM David Rowley <dgrowleyml@gmail.com> wrote:
> >
> > The proposed patches in [1] do aim to make additional usages of the
> > slab allocator, and I have a feeling that we'll want to fix the
> > performance of slab.c before those. Perhaps the Asserts are a better
> > option if we're to get the proposed radix tree implementation.
> 
> Going by [1], that use case is not actually a natural fit for slab because
> of memory fragmentation.
>
> [1]
> https://www.postgresql.org/message-id/20220704220038.at2ane5xkymzzssb%40awork3.anarazel.de

Not so sure about that - IIRC I made one slab for each different size class,
which seemed to work well and suit slab well?

Greetings,

Andres Freund

Commits

  1. Harden memory context allocators against bogus chunk pointers.

  2. Improve our ability to detect bogus pointers passed to pfree et al.

  3. Remove MemoryContextContains().

  4. Remove uses of MemoryContextContains in nodeAgg.c and nodeWindowAgg.c.

  5. Temporarily make MemoryContextContains return false

  6. Make MemoryContextContains work correctly again

  7. Make more effort to put a sentinel at the end of allocated memory

  8. Fix some possibly latent bugs in slab.c

  9. Various cleanups of the new memory context header code

  10. Revert "Add missing padding from MemoryChunk struct"

  11. Use MAXALIGN() in calculations using sizeof(SlabBlock)

  12. Add missing padding from MemoryChunk struct

  13. Improve performance of and reduce overheads of memory management