Hi hackers, One comment in pg_get_shmem_allocations_numa() incorrectly describes the function as dealing with database blocks when it actually processes shared memory allocations from the shmem index.
PFA, a patch to $SUBJECT. Regards, -- Bertrand Drouvot PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
>From 59423c6a83ba69f00c929257f49faa79a19c8662 Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot <bertranddrouvot...@gmail.com> Date: Mon, 21 Jul 2025 08:08:23 +0000 Subject: [PATCH v1] Fix comment in pg_get_shmem_allocations_numa() The comment incorrectly described the function as dealing with database blocks when it actually processes shared memory allocations from the shmem index. --- src/backend/storage/ipc/shmem.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index ca3656fc76f..ff3a738c19c 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -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(); -- 2.34.1
