Date: Tue, 21 Mar 2023 21:19:41 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, sfrost@snowman.net,
	alvherre@alvh.no-ip.org, andres@anarazel.de,
	nathandbossart@gmail.com, jchampion@timescale.com,
	john.naylor@enterprisedb.com, masao.fujii@oss.nttdata.com,
	noriyoshi.shinoda@hpe.com, pgsql-hackers@postgresql.org,
	rjuju123@gmail.com, sawada.mshk@gmail.com, tgl@sss.pgh.pa.us,
	thomas.munro@gmail.com
Subject: Re: Improve logging when using Huge Pages
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On Mon, Mar 20, 2023 at 02:03:13PM +0900, Michael Paquier wrote:
> On Mon, Mar 20, 2023 at 01:54:46PM +0900, Michael Paquier wrote:
> > The main advantage of a read-only GUC over a function is that users
> > would not need to start a postmaster to know if huge pages would be
> > active or not.  This is the main reason why a GUC would be a better
> > fit, in my opinion, because it makes for a cheaper check, while still
> > allowing a SQL query to check the value of the GUC.
> 
> [ Should have read more carefully ]
> 
> ..  Which is something you cannot do with -C because mmap() happens
> after the runtime-computed logic for postgres -C.  It does not sound
> right to do the mmap() for a GUC check, so indeed a function may be
> more adapted rather than move mmap() call a bit earlier in the
> postmaster startup sequence.

On Mon, Mar 20, 2023 at 02:17:33PM +0900, Michael Paquier wrote:
> On Mon, Mar 20, 2023 at 01:09:09AM -0400, Tom Lane wrote:
> > I'm confused here, because Horiguchi-san is saying that that
> > won't work.  I've not checked the code lately, but I think that
> > "postgres -C var" prints its results before actually attempting
> > to establish shared memory, so I suspect Horiguchi-san is right.
> 
> Yes, I haven't read correctly through.  Sorry for the noise.

You set this patch to "waiting on author" twice.  Would you let me know
what I could do to help progress the patch?  Right now, I have no idea.

Most recently, you said it'd be better implemented as a GUC to allow
using -C, but then recanted because -C doesn't work for this (which is
why I implemented it as a string back on 2023-02-08).  Which is why I
reset its status on 2023-03-20.

2023-03-22 01:36:58 	Michael Paquier (michael-kun) 	New status: Waiting on Author
2023-03-20 13:05:32 	Justin Pryzby (justinpryzby) 	New status: Needs review
2023-03-20 05:03:53 	Michael Paquier (michael-kun) 	New status: Waiting on Author

-- 
Justin