Add huge_page_size setting for use on Linux.

This allows the huge page size to be set explicitly.  The default is 0,
meaning it will use the system default, as before.

Author: Odin Ugedal <odin@ugedal.com>
Discussion: https://postgr.es/m/20200608154639.20254-1-odin%40ugedal.com

1 files changed, 31 insertions, 1 deletions

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 031ca0327f0..99a3e4f6f65 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -20,11 +20,14 @@
 #include <float.h>
 #include <math.h>
 #include <limits.h>
-#include <unistd.h>
+#ifndef WIN32
+#include <sys/mman.h>
+#endif
 #include <sys/stat.h>
 #ifdef HAVE_SYSLOG
 #include <syslog.h>
 #endif
+#include <unistd.h>
 
 #include "access/commit_ts.h"
 #include "access/gin.h"
@@ -198,6 +201,7 @@ static bool check_max_wal_senders(int *newval, void **extra, GucSource source);
 static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source);
 static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
 static bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
+static bool check_huge_page_size(int *newval, void **extra, GucSource source);
 static void assign_pgstat_temp_directory(const char *newval, void *extra);
 static bool check_application_name(char **newval, void **extra, GucSource source);
 static void assign_application_name(const char *newval, void *extra);
@@ -576,6 +580,7 @@ int			ssl_renegotiation_limit;
  * need to be duplicated in all the different implementations of pg_shmem.c.
  */
 int			huge_pages;
+int			huge_page_size;
 
 /*
  * These variables are all dummies that don't do anything, except in some
@@ -3381,6 +3386,17 @@ static struct config_int ConfigureNamesInt[] =
 		NULL, assign_tcp_user_timeout, show_tcp_user_timeout
 	},
 
+	{
+		{"huge_page_size", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("The size of huge page that should be requested."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&huge_page_size,
+		0, 0, INT_MAX,
+		check_huge_page_size, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL
@@ -11565,6 +11581,20 @@ check_maintenance_io_concurrency(int *newval, void **extra, GucSource source)
 	return true;
 }
 
+static bool
+check_huge_page_size(int *newval, void **extra, GucSource source)
+{
+#if !(defined(MAP_HUGE_MASK) && defined(MAP_HUGE_SHIFT))
+	/* Recent enough Linux only, for now.  See GetHugePageSize(). */
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("huge_page_size must be 0 on this platform.");
+		return false;
+	}
+#endif
+	return true;
+}
+
 static void
 assign_pgstat_temp_directory(const char *newval, void *extra)
 {