Date: Sun, 6 Nov 2022 07:04:26 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: Thomas Munro <thomas.munro@gmail.com>,
	"Shinoda, Noriyoshi (PN Japan FSIP)" <noriyoshi.shinoda@hpe.com>,
	Jacob Champion <jchampion@timescale.com>,
	Masahiko Sawada <sawada.mshk@gmail.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	pgsql-hackers@postgresql.org, Julien Rouhaud <rjuju123@gmail.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Subject: Re: Improve logging when using Huge Pages
Message-ID: <20221106130426.GG16921@telsasoft.com>
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On Sun, Nov 06, 2022 at 02:04:29PM +0700, John Naylor wrote:
> On Thu, Nov 3, 2022 at 8:11 AM Thomas Munro <thomas.munro@gmail.com> wrote:
> >
> > I wonder if the problem here is that people are reluctant to add noise
> > to every starting system.   There are people who have not configured
> > their system and don't want to see that noise, and then some people
> > have configured their system and would like to know about it if it
> > doesn't work so they can be aware of that, but don't want to use "off"
> > because they don't want a hard failure.  Would it be better if there
> > were a new level "try_log" (or something), which only logs a message
> > if it tries and fails?
> 
> I think the best thing to do is change huge_pages='on' to log a WARNING and
> fallback to regular pages if the mapping fails. That way, both dev and prod
> can keep the same settings, since 'on' will have both visibility and
> robustness. I don't see a good reason to refuse to start -- seems like an
> anti-pattern.

I'm glad to see there's still discussion on this topic :)

Another idea is to add a RUNTIME_COMPUTED GUC to *display* the state of
huge pages, so I can stop parsing /proc/maps to find it.

-- 
Justin