Horton

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

Tomas Vondra <tomas.vondra@enterprisedb.com>

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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>
Cc: 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: 2022-08-30T00:22:55Z
Lists: pgsql-hackers 

On 8/29/22 23:57, Tom Lane wrote:
> David Rowley <dgrowleyml@gmail.com> writes:
>> I've read over the emails and glanced at Tomas' patch. I think that
>> seems good. I think I'd rather see us do that than pad the struct out
>> further as Tomas' method is more aligned to what we do in aset.c
>> (ALLOC_BLOCKHDRSZ) and generation.c (Generation_BLOCKHDRSZ).
> 
>> I can adjust Tomas' patch to #define Slab_BLOCKHDRSZ
> 
> WFM
> 

Same here.

I also suggested doing a similar check in MemoryChunkGetPointer, so that
we catch the issue earlier - right after we allocate the chunk. Any
opinion on that? With an assert only in GetMemoryChunkMethodID() we'd
notice the issue much later, when it may not be obvious if it's a memory
corruption or what. But maybe it's overkill.

regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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