Subject: + lglock-map-to-spinlock-when-config_smp.patch added to -mm tree
To: josh@xxxxxxxxxxxxxxxx,dhowells@xxxxxxxxxx,hpa@xxxxxxxxx,mmarek@xxxxxxx,npiggin@xxxxxxxxx,rusty@xxxxxxxxxxxxxxx,tglx@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 24 Feb 2014 13:17:59 -0800
The patch titled
Subject: lglock: map to spinlock when !CONFIG_SMP
has been added to the -mm tree. Its filename is
lglock-map-to-spinlock-when-config_smp.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lglock-map-to-spinlock-when-config_smp.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lglock-map-to-spinlock-when-config_smp.patch
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------------------------------------------------------
From: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Subject: lglock: map to spinlock when !CONFIG_SMP
When the system has only one CPU, lglock is effectively a spinlock; map it
directly to spinlock to eliminate the indirection and duplicate code.
In addition to removing overhead, this drops 1.6k of code with a defconfig
modified to have !CONFIG_SMP, and 1.1k with a minimal config.
Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/lglock.h | 16 ++++++++++++++++
kernel/locking/Makefile | 3 ++-
2 files changed, 18 insertions(+), 1 deletion(-)
diff -puN include/linux/lglock.h~lglock-map-to-spinlock-when-config_smp include/linux/lglock.h
--- a/include/linux/lglock.h~lglock-map-to-spinlock-when-config_smp
+++ a/include/linux/lglock.h
@@ -25,6 +25,8 @@
#include <linux/cpu.h>
#include <linux/notifier.h>
+#ifdef CONFIG_SMP
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define LOCKDEP_INIT_MAP lockdep_init_map
#else
@@ -57,4 +59,18 @@ void lg_local_unlock_cpu(struct lglock *
void lg_global_lock(struct lglock *lg);
void lg_global_unlock(struct lglock *lg);
+#else
+/* When !CONFIG_SMP, map lglock to spinlock */
+#define lglock spinlock
+#define DEFINE_LGLOCK(name) DEFINE_SPINLOCK(name)
+#define DEFINE_STATIC_LGLOCK(name) static DEFINE_SPINLOCK(name)
+#define lg_lock_init(lg, name) spin_lock_init(lg)
+#define lg_local_lock spin_lock
+#define lg_local_unlock spin_unlock
+#define lg_local_lock_cpu(lg, cpu) spin_lock(lg)
+#define lg_local_unlock_cpu(lg, cpu) spin_unlock(lg)
+#define lg_global_lock spin_lock
+#define lg_global_unlock spin_unlock
+#endif
+
#endif
diff -puN kernel/Makefile~lglock-map-to-spinlock-when-config_smp kernel/Makefile
diff -puN kernel/locking/Makefile~lglock-map-to-spinlock-when-config_smp kernel/locking/Makefile
--- a/kernel/locking/Makefile~lglock-map-to-spinlock-when-config_smp
+++ a/kernel/locking/Makefile
@@ -1,5 +1,5 @@
-obj-y += mutex.o semaphore.o rwsem.o lglock.o
+obj-y += mutex.o semaphore.o rwsem.o
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_lockdep.o = -pg
@@ -14,6 +14,7 @@ ifeq ($(CONFIG_PROC_FS),y)
obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
endif
obj-$(CONFIG_SMP) += spinlock.o
+obj-$(CONFIG_SMP) += lglock.o
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
_
Patches currently in -mm which might be from josh@xxxxxxxxxxxxxxxx are
mm-compactionc-mark-function-as-static.patch
mm-memoryc-mark-functions-as-static.patch
mm-mmapc-mark-function-as-static.patch
mm-process_vm_accessc-mark-function-as-static.patch
mm-process_vm_accessc-mark-function-as-static-fix.patch
mm-page_cgroupc-mark-functions-as-static.patch
mm-nobootmemc-mark-function-as-static.patch
include-linux-mmh-remove-ifdef-condition.patch
include-linux-syscallsh-add-sys32_quotactl-prototype.patch
fs-kernel-permit-disabling-the-uselib-syscall.patch
fs-kernel-permit-disabling-the-uselib-syscall-v2.patch
lglock-map-to-spinlock-when-config_smp.patch
fs-reiserfs-move-prototype-declaration-to-header-file.patch
include-linux-crash_dumph-add-vmcore_cleanup-prototype.patch
include-linux-crash_dumph-add-vmcore_cleanup-prototype-fix.patch
linux-next.patch
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