On Thu, Feb 09, 2023 at 11:29:09AM -0800, Nathan Bossart wrote: > On Thu, Feb 09, 2023 at 10:40:13AM +0100, Alvaro Herrera wrote: > > On 2023-Feb-08, Justin Pryzby wrote: > >> I don't think it makes sense to run postgres -C huge_pages_active, > >> however, so I see no issue that that would always returns "false". > > > > Hmm, I would initialize it to return "unknown" rather than "off" — and > > make sure it turns "off" at the appropriate time. Otherwise you're just > > moving the confusion elsewhere. > > I think this approach would address my concerns about using a GUC.
Done that way. This also fixes the logic in win32_shmem.c. -- Justin
>From 5ead7ba3711dd7a0bb9ec083ebd60049f50f9907 Mon Sep 17 00:00:00 2001 From: Justin Pryzby <pryz...@telsasoft.com> Date: Mon, 23 Jan 2023 18:33:51 -0600 Subject: [PATCH v3] 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. https://www.postgresql.org/message-id/flat/tu4pr8401mb1152ebb0d271f827e2e37a01ee...@tu4pr8401mb1152.namprd84.prod.outlook.com --- doc/src/sgml/config.sgml | 17 ++++++++++++++++- src/backend/port/sysv_shmem.c | 3 +++ src/backend/port/win32_shmem.c | 4 ++++ src/backend/utils/misc/guc_tables.c | 12 ++++++++++++ 4 files changed, 35 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 8c56b134a84..3770c7dc254 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1700,23 +1700,24 @@ include_dir 'conf.d' </indexterm> </term> <listitem> <para> Controls whether huge pages are requested for the main shared memory area. Valid values are <literal>try</literal> (the default), <literal>on</literal>, and <literal>off</literal>. With <varname>huge_pages</varname> set to <literal>try</literal>, the 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> At present, this setting is supported only on Linux and Windows. The setting is ignored on other systems when set to <literal>try</literal>. On Linux, it is only supported when <varname>shared_memory_type</varname> is set to <literal>mmap</literal> (the default). </para> <para> @@ -10679,22 +10680,36 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' with assertions enabled. That is the case if the macro <symbol>USE_ASSERT_CHECKING</symbol> is defined when <productname>PostgreSQL</productname> is built (accomplished e.g., by the <command>configure</command> option <option>--enable-cassert</option>). By default <productname>PostgreSQL</productname> is built without assertions. </para> </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> <primary><varname>integer_datetimes</varname> configuration parameter</primary> </indexterm> </term> <listitem> <para> Reports whether <productname>PostgreSQL</productname> was built with support for 64-bit-integer dates and times. As of <productname>PostgreSQL</productname> 10, this is always <literal>on</literal>. diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index eaba244bc9c..48ead4d27bf 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -619,22 +619,25 @@ CreateAnonymousSegment(Size *size) allocsize += hugepagesize - (allocsize % hugepagesize); 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); } #endif + SetConfigOption("huge_pages_active", ptr == MAP_FAILED ? "off" : "on", + PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT); + if (ptr == MAP_FAILED && huge_pages != HUGE_PAGES_ON) { /* * Use the original size, not the rounded-up value, when falling back * to non-huge pages. */ allocsize = *size; ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE, PG_MMAP_FLAGS, -1, 0); mmap_errno = errno; } diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c index 62e08074770..0bf594c8bf9 100644 --- a/src/backend/port/win32_shmem.c +++ b/src/backend/port/win32_shmem.c @@ -319,22 +319,26 @@ retry: * If the segment already existed, CreateFileMapping() will return a * handle to the existing one and set ERROR_ALREADY_EXISTS. */ if (GetLastError() == ERROR_ALREADY_EXISTS) { CloseHandle(hmap); /* Close the handle, since we got a valid one * to the previous segment. */ hmap = NULL; Sleep(1000); continue; } + + SetConfigOption("huge_pages_active", (flProtect & SEC_LARGE_PAGES) ? + "on" : "off", PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT); + break; } /* * If the last call in the loop still returned ERROR_ALREADY_EXISTS, this * shared memory segment exists and we assume it belongs to somebody else. */ if (!hmap) ereport(FATAL, (errmsg("pre-existing shared memory block is still in use"), errhint("Check if there are any old server processes still running, and terminate them."))); diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index b21698934c8..1a298f16c81 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -554,22 +554,23 @@ static int server_version_num; #define DEFAULT_SYSLOG_FACILITY LOG_LOCAL0 #else #define DEFAULT_SYSLOG_FACILITY 0 #endif static int syslog_facility = DEFAULT_SYSLOG_FACILITY; static char *timezone_string; static char *log_timezone_string; static char *timezone_abbreviations_string; static char *data_directory; static char *session_authorization_string; +static char *huge_pages_active = "unknown"; /* dynamically set */ static int max_function_args; static int max_index_keys; static int max_identifier_length; static int block_size; static int segment_size; 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 integer_datetimes; @@ -4516,22 +4517,33 @@ struct config_string ConfigureNamesString[] = { {"backtrace_functions", PGC_SUSET, DEVELOPER_OPTIONS, gettext_noop("Log backtrace for errors in these functions."), NULL, GUC_NOT_IN_SAMPLE }, &backtrace_functions, "", check_backtrace_functions, assign_backtrace_functions, 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, + "unknown", + NULL, NULL, NULL + }, + /* End-of-list marker */ { {NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL } }; struct config_enum ConfigureNamesEnum[] = { { {"backslash_quote", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS, -- 2.34.1
