On Wed, Nov 09, 2022 at 02:04:00PM +0900, Michael Paquier wrote:
> On Wed, Nov 09, 2022 at 11:47:57AM +0900, Kyotaro Horiguchi wrote:
> > Honestly I don't come up with other users of the new
> > log-level. Another possible issue is it might be a bit hard for people
> > to connect that level to huge_pages=try, whereas I think we shouldn't
> > put a description about the concrete impact range of that log-level.
> >
> > I came up with an alternative idea that add a new huge_pages value
> > try_report or try_verbose, which tell postgresql to *always* report
> > the result of huge_pages = try.
>
> Here is an extra idea for the bucket of ideas: switch the user-visible
> value of huge_pages to 'on' when we are at "try" but success in using
> huge pages, and switch the visible value to "off". The idea of Justin
> in [1] to use an internal runtime-computed GUC sounds sensible, as well
> (say a boolean effective_huge_pages?).
>
> [1]:
> https://www.postgresql.org/message-id/20221106130426.gg16...@telsasoft.com
> --
> Michael
Michael seemed to support this idea and nobody verbalized hatred of it,
so I implemented it. In v15, we have shared_memory_size_in_huge_pages,
so this adds effective_huge_pages.
Feel free to suggest a better name.
--
Justin
>From 2bb0c48dfefff78325b1b9d31a3e54e982d44e4e 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: effective_huge_pages
This is useful to show the current state of huge pages when
huge_pages=try.
---
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 | 12 ++++++++++++
4 files changed, 41 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f985afc009d..383139d5266 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-effective-huge-pages"/>.
</para>
<para>
@@ -10687,6 +10688,20 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
</listitem>
</varlistentry>
+ <varlistentry id="guc-effective-huge-pages" xreflabel="effective_huge_pages">
+ <term><varname>effective_huge_pages</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>effective_huge_pages</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..1e6adc97533 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("effective_huge_pages", "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..8c5ffd7af4c 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("effective_huge_pages", "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..88272765479 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 effective_huge_pages;
static bool integer_datetimes;
#ifdef USE_ASSERT_CHECKING
@@ -1972,6 +1973,17 @@ struct config_bool ConfigureNamesBool[] =
NULL, NULL, NULL
},
+ {
+ {"effective_huge_pages", 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
+ },
+ &effective_huge_pages,
+ false,
+ NULL, NULL, NULL
+ },
+
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL
--
2.25.1
