Messages in this thread Patch in this message | | | Date | Fri, 25 Oct 2013 16:19:37 +0100 | From | Josh Triplett <> | Subject | [PATCH] lglock: Map to spinlock when !CONFIG_SMP |
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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@joshtriplett.org> --- include/linux/lglock.h | 16 ++++++++++++++++ kernel/Makefile | 4 ++-- 2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/include/linux/lglock.h b/include/linux/lglock.h index 0d24e93..6561b1c 100644 --- a/include/linux/lglock.h +++ b/include/linux/lglock.h @@ -35,6 +35,8 @@ #define DEFINE_BRLOCK(name) DEFINE_LGLOCK(name) #define DEFINE_STATIC_BRLOCK(name) DEFINE_STATIC_LGLOCK(name) +#ifdef CONFIG_SMP + #ifdef CONFIG_DEBUG_LOCK_ALLOC #define LOCKDEP_INIT_MAP lockdep_init_map #else @@ -67,4 +69,18 @@ void lg_local_unlock_cpu(struct lglock *lg, int cpu); 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 --git a/kernel/Makefile b/kernel/Makefile index 1ce4755..84a89f7 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -10,7 +10,7 @@ obj-y = fork.o exec_domain.o panic.o \ kthread.o wait.o sys_ni.o posix-cpu-timers.o mutex.o \ hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \ notifier.o ksysfs.o cred.o reboot.o \ - async.o range.o groups.o lglock.o smpboot.o + async.o range.o groups.o smpboot.o ifdef CONFIG_FUNCTION_TRACER # Do not trace debug files and internal ftrace files @@ -50,7 +50,7 @@ obj-$(CONFIG_SMP) += smp.o ifneq ($(CONFIG_SMP),y) obj-y += up.o endif -obj-$(CONFIG_SMP) += spinlock.o +obj-$(CONFIG_SMP) += lglock.o spinlock.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o obj-$(CONFIG_UID16) += uid16.o -- 1.8.4.rc3
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