Hi,
Attached you can find a short (compile tested only ) patch implementing
a 'shared_memory_type' GUC, akin to 'dynamic_shared_memory_type'. Will
only apply to 9.4, not 9.3, but it should be easy to convert for it.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
>From e090326d8b5933a162e8e503ccec714bde3a49b7 Mon Sep 17 00:00:00 2001
From: Andres Freund <and...@anarazel.de>
Date: Tue, 22 Apr 2014 14:17:34 +0200
Subject: [PATCH] Add shared_memory_type GUC.
---
src/backend/port/sysv_shmem.c | 18 ++++++++++++------
src/backend/storage/ipc/ipci.c | 2 ++
src/backend/utils/misc/guc.c | 23 +++++++++++++++++++++++
src/backend/utils/misc/postgresql.conf.sample | 7 ++++++-
src/include/storage/pg_shmem.h | 21 +++++++++++++++++++--
5 files changed, 62 insertions(+), 9 deletions(-)
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index 5e3850b..f6343d3 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -465,14 +465,20 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port,
* developer use, this shouldn't be a big problem.
*/
#ifndef EXEC_BACKEND
- AnonymousShmem = CreateAnonymousSegment(&size);
- AnonymousShmemSize = size;
+ if (shared_memory_type == SHMEM_TYPE_MMAP)
+ {
+ AnonymousShmem = CreateAnonymousSegment(&size);
+ AnonymousShmemSize = size;
- /* Now we need only allocate a minimal-sized SysV shmem block. */
- sysvsize = sizeof(PGShmemHeader);
-#else
- sysvsize = size;
+ /* Now we need only allocate a minimal-sized SysV shmem block. */
+ sysvsize = sizeof(PGShmemHeader);
+ }
+ else
#endif
+ {
+ Assert(shared_memory_type == SHMEM_TYPE_SYSV);
+ sysvsize = size;
+ }
/* Make sure PGSharedMemoryAttach doesn't fail without need */
UsedShmemSegAddr = NULL;
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 4290d2d..c58f171 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -42,6 +42,8 @@
#include "storage/sinvaladt.h"
#include "storage/spin.h"
+/* GUCs */
+int shared_memory_type = DEFAULT_SHARED_MEMORY_TYPE;
shmem_startup_hook_type shmem_startup_hook = NULL;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea54d16..f6d9dc4 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -403,6 +403,19 @@ static const struct config_enum_entry huge_pages_options[] = {
{NULL, 0, false}
};
+static struct config_enum_entry shared_memory_options[] = {
+#ifndef WIN32
+ { "sysv", SHMEM_TYPE_SYSV, false},
+#endif
+#ifndef EXEC_BACKEND
+ { "mmap", SHMEM_TYPE_MMAP, false},
+#endif
+#ifdef WIN32
+ { "windows", SHMEM_TYPE_WINDOWS, false},
+#endif
+ {NULL, 0, false}
+};
+
/*
* Options for enum values stored in other modules
*/
@@ -3453,6 +3466,16 @@ static struct config_enum ConfigureNamesEnum[] =
},
{
+ {"shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
+ gettext_noop("Selects the shared memory implementation used."),
+ NULL
+ },
+ &shared_memory_type,
+ DEFAULT_SHARED_MEMORY_TYPE, shared_memory_options,
+ NULL, NULL, NULL
+ },
+
+ {
{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
gettext_noop("Selects the method used for forcing WAL updates to disk."),
NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 70e5a51..1c5f02a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -127,7 +127,12 @@
#maintenance_work_mem = 64MB # min 1MB
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB # min 100kB
-#dynamic_shared_memory_type = posix # the default is the first option
+#shared_memory_type = mmap # the default is the first option
+ # supported by the operating system:
+ # mmap
+ # sysv
+ # windows
+#dynamic_shared_memory_type = posix # the default is the first option
# supported by the operating system:
# posix
# sysv
diff --git a/src/include/storage/pg_shmem.h b/src/include/storage/pg_shmem.h
index ab28ebe..53ea43a 100644
--- a/src/include/storage/pg_shmem.h
+++ b/src/include/storage/pg_shmem.h
@@ -41,8 +41,13 @@ typedef struct PGShmemHeader /* standard header for all Postgres shmem */
#endif
} PGShmemHeader;
-/* GUC variable */
-extern int huge_pages;
+/* Possible values for shared_memory_type */
+typedef enum
+{
+ SHMEM_TYPE_WINDOWS,
+ SHMEM_TYPE_SYSV,
+ SHMEM_TYPE_MMAP
+} PGShmemType;
/* Possible values for huge_pages */
typedef enum
@@ -52,6 +57,10 @@ typedef enum
HUGE_PAGES_TRY
} HugePagesType;
+/* GUC variables */
+extern int shared_memory_type;
+extern int huge_pages;
+
#ifndef WIN32
extern unsigned long UsedShmemSegID;
#else
@@ -59,6 +68,14 @@ extern HANDLE UsedShmemSegID;
#endif
extern void *UsedShmemSegAddr;
+#if !defined(WIN32) && !defined(EXEC_BACKEND)
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_MMAP
+#elif !defined(WIN32)
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_SYSV
+#else
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_WINDOWS
+#endif
+
#ifdef EXEC_BACKEND
extern void PGSharedMemoryReAttach(void);
#endif
--
1.8.5.rc2.dirty
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