Horton

Re: Estimating HugePages Requirements?

Julien Rouhaud <rjuju123@gmail.com>

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From: Julien Rouhaud <rjuju123@gmail.com>
To: Don Seiler <don@seiler.us>
Cc: pgsql-admin <pgsql-admin@postgresql.org>
Date: 2021-06-09T17:23:28Z
Lists: pgsql-hackers 
On Thu, Jun 10, 2021 at 12:42 AM Don Seiler <don@seiler.us> wrote:
>
> I'm told other factors contribute to this additional memory requirement, such as max_connections, wal_buffers, etc. I'm wondering if anyone has been able to come up with a reliable method for determining the HugePages requirements for a PG cluster based on the GUC values (that would be known at deployment time).

It also depends on modules like pg_stat_statements and their own
configuration.  I think that you can find the required size that your
current configuration will allocate with:

SELECT sum(allocated_size) FROM pg_shmem_allocations ;

Commits

  1. Silence extra logging when using "postgres -C" on runtime-computed GUCs

  2. doc: Improve postgres command for shared_memory_size_in_huge_pages

  3. Introduce GUC shared_memory_size_in_huge_pages

  4. Support "postgres -C" with runtime-computed GUCs

  5. Make shared_memory_size a preset option

  6. Introduce GUC shared_memory_size

  7. Move the shared memory size calculation to its own function

  8. Add new GUC, max_worker_processes, limiting number of bgworkers.