Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 22 Mar 2023 16:37:01 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Justin Pryzby <pryzby@telsasoft.com>
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
Message-ID: <ZBqwHY7yZQATAp9N@paquier.xyz>
References: <ZBfsbTEUnRcEyNao@paquier.xyz>
 <ZBplvQx7n0MGVr6O@telsasoft.com>
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On Tue, Mar 21, 2023 at 09:19:41PM -0500, Justin Pryzby wrote:
> 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.

My mistake, I've been looking at an incorrect version of the patch.
Thanks for correcting me here.

I have read through the proposed v5 of the patch, that seems to be the
latest one available:
https://www.postgresql.org/message-id/ZA+Bpk/6LcYiUXnh@telsasoft.com

I have noted something..  For the WIN32 case, we have that:

+++ b/src/backend/port/win32_shmem.c
@@ -327,6 +327,8 @@ retry:
            Sleep(1000);
            continue;
        }
+
+       huge_pages_active = ((flProtect & SEC_LARGE_PAGES) != 0);
        break;

Are you sure that this is correct?  This is set in
PGSharedMemoryCreate(), part of CreateSharedMemoryAndSemaphores() in
the startup sequence that creates the shmem segment.  However, for a
normal backend created by EXEC_BACKEND, SubPostmasterMain() reattaches
to an existing shared memory segment, so we don't go through the
creation path that would set huge_pages_active for the process just
started, (note that InitPostmasterChild() switches IsUnderPostmaster,
bypassing the shmem segment creation).
--
Michael

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