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Fix comment in pg_get_shmem_allocations_numa()

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The comment fixed in this commit described the function as dealing with
database blocks, but in reality it processes shared memory allocations.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aH4DDhdiG9Gi0rG7@ip-10-97-1-34.eu-west-3.compute.internal
Backpatch-through: 18
This commit is contained in:
Michael Paquier
2025-10-21 16:12:30 +09:00
parent 18d2614093
commit e4e496e88c
1 changed files with 6 additions and 9 deletions
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15
src/backend/storage/ipc/shmem.c
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@@ -606,16 +606,13 @@ pg_get_shmem_allocations_numa(PG_FUNCTION_ARGS)
nodes = palloc(sizeof(Size) * (max_nodes + 1));
/*
* Different database block sizes (4kB, 8kB, ..., 32kB) can be used, while
* the OS may have different memory page sizes.
* Shared memory allocations can vary in size and may not align with OS
* memory page boundaries, while NUMA queries work on pages.
*
* To correctly map between them, we need to: 1. Determine the OS memory
* page size 2. Calculate how many OS pages are used by all buffer blocks
* 3. Calculate how many OS pages are contained within each database
* block.
*
* This information is needed before calling move_pages() for NUMA memory
* node inquiry.
* To correctly map each allocation to NUMA nodes, we need to: 1.
* Determine the OS memory page size. 2. Align each allocation's start/end
* addresses to page boundaries. 3. Query NUMA node information for all
* pages spanning the allocation.
*/
os_page_size = pg_get_shmem_pagesize();