On Tue, Jan 24, 2023 at 07:37:29PM -0600, Justin Pryzby wrote:
> BTW, I didn't realize it when I made the suggestion, nor when I wrote
> the patch, but a GUC was implemented in the v2 patch.
> https://www.postgresql.org/message-id/TU4PR8401MB1152CB4FEB99658BC6B35543EECF9%40TU4PR8401MB1152.NAMPRD84.PROD.OUTLOOK.COM
> Whether it's a GUC or a function, I propose to name it hugepages_active.
> If there's no objections, I'll add to the CF.
As such, I re-opened the previous CF.
https://commitfest.postgresql.org/38/3310/
>From f23e27ed112aff2f177082a105d79aaa09b2ce3b Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryz...@telsasoft.com>
Date: Mon, 23 Jan 2023 18:33:51 -0600
Subject: [PATCH] add GUC: huge_pages_active
This is useful to show the current state of huge pages when
huge_pages=try. The effective status is not otherwise visible without
OS level tools like gdb or /proc/N/smaps.
---
doc/src/sgml/config.sgml | 17 ++++++++++++++++-
src/backend/port/sysv_shmem.c | 12 +++++++++---
src/backend/port/win32_shmem.c | 4 ++++
src/backend/utils/misc/guc_tables.c | 13 +++++++++++++
4 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f985afc009d..e5ef58d441d 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1708,7 +1708,8 @@ include_dir 'conf.d'
server will try to request huge pages, but fall back to the default if
that fails. With <literal>on</literal>, failure to request huge pages
will prevent the server from starting up. With <literal>off</literal>,
- huge pages will not be requested.
+ huge pages will not be requested. The actual state of huge pages is
+ indicated by the server variable <xref linkend="guc-huge-pages-active"/>.
</para>
<para>
@@ -10687,6 +10688,20 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
</listitem>
</varlistentry>
+ <varlistentry id="guc-huge-pages-active" xreflabel="huge_pages_active">
+ <term><varname>huge_pages_active</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>huge_pages_active</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Reports whether huge pages are in use by the current process.
+ See <xref linkend="guc-huge-pages"/> for more information.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-integer-datetimes" xreflabel="integer_datetimes">
<term><varname>integer_datetimes</varname> (<type>boolean</type>)
<indexterm>
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index eaba244bc9c..62029e7fe0e 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -621,9 +621,15 @@ CreateAnonymousSegment(Size *size)
ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
PG_MMAP_FLAGS | mmap_flags, -1, 0);
mmap_errno = errno;
- if (huge_pages == HUGE_PAGES_TRY && ptr == MAP_FAILED)
- elog(DEBUG1, "mmap(%zu) with MAP_HUGETLB failed, huge pages disabled: %m",
- allocsize);
+ if (huge_pages == HUGE_PAGES_TRY)
+ {
+ if (ptr == MAP_FAILED)
+ elog(DEBUG1, "mmap(%zu) with MAP_HUGETLB failed, huge pages disabled: %m",
+ allocsize);
+ else
+ SetConfigOption("huge_pages_active", "on",
+ PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
+ }
}
#endif
diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c
index 62e08074770..352e68b7af2 100644
--- a/src/backend/port/win32_shmem.c
+++ b/src/backend/port/win32_shmem.c
@@ -314,6 +314,10 @@ retry:
errdetail("Failed system call was CreateFileMapping(size=%zu, name=%s).",
size, szShareMem)));
}
+ else if (huge_pages == HUGE_PAGES_TRY)
+ SetConfigOption("huge_pages_active", "on",
+ PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
+
/*
* If the segment already existed, CreateFileMapping() will return a
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 4454d57322a..649aa473020 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -571,6 +571,7 @@ static int shared_memory_size_mb;
static int shared_memory_size_in_huge_pages;
static int wal_block_size;
static bool data_checksums;
+static bool huge_pages_active = false; /* dynamically set */
static bool integer_datetimes;
#ifdef USE_ASSERT_CHECKING
@@ -1013,6 +1014,18 @@ struct config_bool ConfigureNamesBool[] =
true,
NULL, NULL, NULL
},
+
+ {
+ {"huge_pages_active", PGC_INTERNAL, PRESET_OPTIONS,
+ gettext_noop("Indicates whether huge pages are in use."),
+ NULL,
+ GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_RUNTIME_COMPUTED
+ },
+ &huge_pages_active,
+ false,
+ NULL, NULL, NULL
+ },
+
{
/* Not for general use --- used by SET SESSION AUTHORIZATION */
{"is_superuser", PGC_INTERNAL, UNGROUPED,
--
2.25.1
