Horton

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

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, Amit Kapila <amit.kapila16@gmail.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2022-08-30T03:21:49Z
Lists: pgsql-hackers 
On Tue, 30 Aug 2022 at 15:15, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> AFAICS that could only happen if "double" has 8-byte alignment
> requirement but int64 does not.  I recall some discussion about
> that possibility a month or two back, but I think we concluded
> that we weren't going to support it.

ok

> I guess what I mostly don't like about df0f4feef is the hardwired "8"
> constants.  Yeah, it's hard to see how sizeof(uint64) isn't 8, but
> it's not very readable like this IMO.

Yeah, that was just down to lack of any SIZEOF_* macro to tell me
uint64 was 8 bytes.

I can revert df0f4feef, but would prefer just to get the green light
for d5ee4db0e from those 32-bit arm animals before doing so.

David

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