Re: pgsql: Introduce pg_shmem_allocations_numa view

On 6/23/25 22:31, Christoph Berg wrote:
> Re: Tomas Vondra
>> Huh. So it's only the first call that does this?
> 
> The first call after a restart. Reconnecting is not enough.
> 
>> Can you maybe print the addresses passed to pg_numa_query_pages? I
> 
> The addresses look good:
> 
> Breakpoint 1, pg_numa_query_pages (pid=0, count=32768, pages=0xeb44d02c, status=0xeb42c02c) at
../src/port/pg_numa.c:49
> 49        return numa_move_pages(pid, count, pages, NULL, status, 0);
> (gdb) p *pages
> $1 = (void *) 0xebc33000
> (gdb) p pages[1]
> $2 = (void *) 0xebc34000
> (gdb) p pages[2]
> $3 = (void *) 0xebc35000
> 

Didn't you say the first ~35 addresses succeed, right? What about the
addresses after that?

> 
>> wonder if there's some bug in how we fill that array. Not sure why would
>> it happen only on 32-bit systems, though.
> 
> I found something, but that should be harmless:
> 
> --- a/contrib/pg_buffercache/pg_buffercache_pages.c
> +++ b/contrib/pg_buffercache/pg_buffercache_pages.c
> @@ -365,7 +365,7 @@ pg_buffercache_numa_pages(PG_FUNCTION_ARGS)
> 
>          /* Used to determine the NUMA node for all OS pages at once */
>          os_page_ptrs = palloc0(sizeof(void *) * os_page_count);
> -        os_page_status = palloc(sizeof(uint64) * os_page_count);
> +        os_page_status = palloc(sizeof(int) * os_page_count);
> 

Yes, good catch. But as you say, that should be benign - we allocate
more memory than needed, I don't think it should break anything.


-- 
Tomas Vondra