Re: huge_page_size parameter description in the pg 14 docs is not exact

On Wed, Jul 20, 2022 at 09:56:37PM +0800, yanliang lei wrote:
> 
> https://www.postgresql.org/docs/15/runtime-config-resource.html#
> GUC-HUGE-PAGE-SIZE
> 
> 
> the following is from the above website:
> 
> Some commonly available page sizes on modern 64 bit server architectures
> include: 
> 
> 2MB and 1GB (Intel and AMD), 16MB and 16GB (IBM POWER), and 64kB, 2MB, 32MB and
> 1GB (ARM). For more information about usage and support,

I think these are the sizes the CPUs support, no necessarily the ones
that the operating system supports.

> but after my test, I found that: 
> 
> in the RHEL7.9(kernel version 3.10.0-1160),when I set the non default huge page
> size for huge_page_size parameter ,PG14 can not start；
> 
> in the RHEL8.5(kernel version 4.18.0-348),when I set the non default huge page
> size for huge_page_size parameter ,PG14 can start 。

The paragraph begins with:

    Some commonly available page sizes on modern 64 bit server
    architectures include:

which seems sufficient to suggest that all listed sizes might not be
supported on all operating systems, and this is only supported on Linux,
as documented.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

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