Re: Different memory allocation strategy in Postgres 11?

On Sat, Oct 27, 2018 at 6:10 AM Thomas Kellerer <spam_eater(at)gmx(dot)net> wrote:
> Jeff Janes schrieb am 26.10.2018 um 17:42:
> > I typically configure "shared_buffers = 4096MB" on my 16GB system as sometimes when testing, it pays off to have a bigger cache.
> >
> > With Postgres 10 and earlier, the Postgres process(es) would only allocate that memory from the operating system when needed.
> > So right after startup, it would only consume several hundred MB, not the entire 4GB
> >
> > However with Postgres 11 I noticed that it immediately grabs the complete memory configured for shared_buffers during startup.
> >
> > It's not really a big deal, but I wonder if that is an intentional change or a result from something else?
> >
> >
> > Do you have pg_prewarm in shared_preload_libraries?
>
> No. The only shared libraries are those for pg_stat_statemens

Does your user have "Lock Pages in Memory" privilege? One thing that
is new in 11 is huge AKA large page support, and the default is
huge_pages=try. Not a Windows person myself but I believe that should
succeed if you have that privilege and enough contiguous chunks of
physical memory are available. If you set huge_pages=off does it
revert to the old behaviour?

--
Thomas Munro
http://www.enterprisedb.com