Re: PGPROC alignment (was Re: pgsql: Separate RecoveryConflictReasons from procsignals)

On 11/02/2026 06:40, Bertrand Drouvot wrote:
> A few comments:
>
> 0001:
>
> + * and (b) to make the multiplication / division to convert between PGPROC *
> + * and ProcNumber be a little cheaper
>
> Is that correct if PGPROC size is not a power of 2?

You're right, it's not.

> 0002: Good catch!

Committed that.

>> With this, sizeof(PGPROC) == 864 without the explicit alignment to
>> PG_CACHE_LINE_SIZE, and 896 with it.
>
> I can see 876 -> 896 on my side:
>
> /* 872 | 4 */ uint32 wait_event_info;
> /* XXX 20-byte padding */
>
> /* total size (bytes): 896 */
> }

Interesting. I've attached 'pahole bin/postgres' output from my laptop.
It's Linux on arm64. This is with my v2 patches to rearrange the fields,
but with the "pg_attribute_aligned(PG_CACHE_LINE_SIZE)" removed.

- Heikki