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

On Thu, Jul 21, 2022 at 2:03 AM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> 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.

Yeah, that's just some sizes that the architecture *might* support.
Some eg laptop x86 chips might not have 1GB pages. You could look at
the output of the cpuid program on Linux, or find similar info in
dmesg etc. Then you need to tell the kernel to make some pages
available. This message has some info from my testing of
huge_page_size:

https://www.postgresql.org/message-id/CA%2BhUKG%2BgdWThHi0v6TmiLgUE_rqqQ%2BPKw2t%2BkT6w08H36qzxpw%40mail.gmail.com