From 46c6ada322517c4246ea16597475c392d0b33005 Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Tue, 7 Sep 2021 16:46:52 +0000 Subject: [PATCH v7 2/3] Introduce huge_pages_required GUC. This runtime-computed GUC shows the number of huge pages required for the server's main shared memory area. Like shared_memory_size, it cannot be viewed with 'postgres -C' yet. --- doc/src/sgml/config.sgml | 21 +++++++++++++++++++++ src/backend/port/sysv_shmem.c | 16 +++++++++++----- src/backend/port/win32_shmem.c | 14 ++++++++++++++ src/backend/storage/ipc/ipci.c | 12 ++++++++++++ src/backend/utils/misc/guc.c | 12 ++++++++++++ src/include/storage/pg_shmem.h | 1 + 6 files changed, 71 insertions(+), 5 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index ef0e2a7746..b27d8aff15 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -10101,6 +10101,27 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' + + huge_pages_required (integer) + + huge_pages_required configuration parameter + + + + + Reports the number of huge pages that are required for the main + shared memory area based on the specified + . If huge pages are not supported, + this will be -1. + + + This setting is supported only on Linux. It is always set to + -1 on other platforms. For more details about using + huge pages on Linux, see . + + + + integer_datetimes (boolean) diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 9de96edf6a..125e2d47ec 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -456,8 +456,6 @@ PGSharedMemoryAttach(IpcMemoryId shmId, return shmStat.shm_nattch == 0 ? SHMSTATE_UNATTACHED : SHMSTATE_ATTACHED; } -#ifdef MAP_HUGETLB - /* * Identify the huge page size to use, and compute the related mmap flags. * @@ -476,11 +474,19 @@ PGSharedMemoryAttach(IpcMemoryId shmId, * such as increasing shared_buffers to absorb the extra space. * * Returns the (real, assumed or config provided) page size into *hugepagesize, - * and the hugepage-related mmap flags to use into *mmap_flags. + * and the hugepage-related mmap flags to use into *mmap_flags. If huge pages + * is not supported, *hugepagesize and *mmap_flags will be set to 0. */ -static void +void GetHugePageSize(Size *hugepagesize, int *mmap_flags) { +#ifndef MAP_HUGETLB + + *hugepagesize = 0; + *mmap_flags = 0; + +#else + Size default_hugepagesize = 0; /* @@ -553,9 +559,9 @@ GetHugePageSize(Size *hugepagesize, int *mmap_flags) *mmap_flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT; } #endif -} #endif /* MAP_HUGETLB */ +} /* * Creates an anonymous mmap()ed shared memory segment. diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c index d7a71992d8..90de2ab4e1 100644 --- a/src/backend/port/win32_shmem.c +++ b/src/backend/port/win32_shmem.c @@ -605,3 +605,17 @@ pgwin32_ReserveSharedMemoryRegion(HANDLE hChild) return true; } + +/* + * This function is provided for consistency with sysv_shmem.c and does not + * provide any useful information for Windows. To obtain the large page size, + * use GetLargePageMinimum() instead. + * + * This always sets *hugepagesize and *mmap_flags to 0. + */ +void +GetHugePageSize(Size *hugepagesize, int *mmap_flags) +{ + *hugepagesize = 0; + *mmap_flags = 0; +} diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 4b7b2faa4c..14de7afe0a 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -326,6 +326,9 @@ InitializeShmemGUCs(void) char buf[64]; Size size_b; Size size_mb; + Size hp_size; + Size hp_required; + int unused; /* * Calculate the shared memory size and round up to the nearest @@ -335,4 +338,13 @@ InitializeShmemGUCs(void) size_mb = add_size(size_b, (1024 * 1024) - 1) / (1024 * 1024); sprintf(buf, "%lu", size_mb); SetConfigOption("shared_memory_size", buf, PGC_INTERNAL, PGC_S_OVERRIDE); + + /* Calculate the number of huge pages required */ + GetHugePageSize(&hp_size, &unused); + if (hp_size != 0) + { + hp_required = (size_b / hp_size) + 1; + sprintf(buf, "%lu", hp_required); + SetConfigOption("huge_pages_required", buf, PGC_INTERNAL, PGC_S_OVERRIDE); + } } diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index a11387c5ce..1a30d635fc 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -621,6 +621,7 @@ char *pgstat_temp_directory; char *application_name; int shmem_size_mb; +int huge_pages_required; int tcp_keepalives_idle; int tcp_keepalives_interval; @@ -2225,6 +2226,17 @@ static struct config_int ConfigureNamesInt[] = NULL, NULL, NULL }, + { + {"huge_pages_required", PGC_INTERNAL, RESOURCES_MEM, + gettext_noop("Shows the number of huge pages needed for the main shared memory area."), + gettext_noop("-1 indicates that the value could not be determined."), + GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE + }, + &huge_pages_required, + -1, -1, INT_MAX, + NULL, NULL, NULL + }, + { /* This is PGC_SUSET to prevent hiding from log_lock_waits. */ {"deadlock_timeout", PGC_SUSET, LOCK_MANAGEMENT, diff --git a/src/include/storage/pg_shmem.h b/src/include/storage/pg_shmem.h index 059df1b72c..518eb86065 100644 --- a/src/include/storage/pg_shmem.h +++ b/src/include/storage/pg_shmem.h @@ -87,5 +87,6 @@ extern PGShmemHeader *PGSharedMemoryCreate(Size size, PGShmemHeader **shim); extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2); extern void PGSharedMemoryDetach(void); +extern void GetHugePageSize(Size *hugepagesize, int *mmap_flags); #endif /* PG_SHMEM_H */ -- 2.16.6