Re: pgsql: Introduce pg_shmem_allocations_numa view

Tomas Vondra <tomas@vondra.me>

From: Tomas Vondra <tomas@vondra.me>

To: Christoph Berg <myon@debian.org>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

Cc: Andres Freund <andres@anarazel.de>, Tomas Vondra <tomas.vondra@postgresql.org>, pgsql-hackers@lists.postgresql.org

Date: 2025-06-25T09:22:41Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Handle EPERM in pg_numa_init
- 599336c64fc9 19 (unreleased) landed
- 482e98ac4302 18.2 landed
Add CHECK_FOR_INTERRUPTS into pg_numa_query_pages
- 54ac4944c36f 18.0 landed
- bf1119d74a79 19 (unreleased) landed
Silence valgrind about pg_numa_touch_mem_if_required
- 14e52227e578 18.0 landed
- 81f287dc923f 19 (unreleased) landed
Limit the size of numa_move_pages requests
- 45879f48f140 18.0 landed
- 7fe2f67c7c9f 19 (unreleased) landed
Introduce pg_shmem_allocations_numa view
- 8cc139bec34a 18.0 cited

On 6/25/25 11:00, Christoph Berg wrote:
> Re: Bertrand Drouvot
>> +/*
>> + * Work around Linux kernel bug in 32-bit compat mode: do_pages_stat() has
>> + * incorrect pointer arithmetic for more than DO_PAGES_STAT_CHUNK_NR pages.
>> + */
>> +#if SIZEOF_SIZE_T == 4
> 
> I was also missing it in my suggested patch draft, but this should
> probably include #ifdef __linux__.
> 

> 
> Re: Tomas Vondra
>> +#ifdef USE_VALGRIND
>> +
>> +static inline void
>> +pg_numa_touch_mem_if_required(uint64 tmp, char *ptr)
> 
> Stupid question, if this function gets properly inlined, why not
> always use it as there should be no performance difference vs using a
> macro?
> 

TBH I'm not 100% sure it works correctly, I need to check it actually
touches the memory etc. It's possible it was discussed in one of the
earlier NUMA threads, and there are reasons to do a macro.

I also dislike the ifdefs because it adds subtle differences between the
"normal" code and the code tested with valgrind. So just having the
inlined function would be "nicer".

regards

-- 
Tomas Vondra