Josh Triplett <[email protected]> writes: > 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 <[email protected]>
Nice. Looks like a patch for Andrew Morton though. Cheers, Rusty. > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
