From 3405d230b374b6923878b21b8d708d7db1f734ef Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Wed, 15 Jan 2014 18:14:28 +1100 Subject: powerpc: Add support for the optimised lockref implementation This commit adds the architecture support required to enable the optimised implementation of lockrefs. That's as simple as defining arch_spin_value_unlocked() and selecting the Kconfig option. We also define cmpxchg64_relaxed(), because the lockref code does not need the cmpxchg to have barrier semantics. Using Linus' test case[1] on one system I see a 4x improvement for the basic enablement, and a further 1.3x for cmpxchg64_relaxed(), for a total of 5.3x vs the baseline. On another system I see more like 2x improvement. [1]: http://marc.info/?l=linux-fsdevel&m=137782380714721&w=4 Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/spinlock.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/powerpc/include/asm/spinlock.h') diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 5f54a744dcc5..5162f8cd18c0 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -54,6 +54,11 @@ #define SYNC_IO #endif +static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) +{ + return lock.slock == 0; +} + /* * This returns the old value in the lock, so we succeeded * in getting the lock if the return value is 0. -- cgit From 7179ba52889bef7e5e23f72908270e1ab2b7fc6f Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Wed, 15 Jan 2014 18:14:29 +1100 Subject: powerpc: Implement arch_spin_is_locked() using arch_spin_value_unlocked() At a glance these are just the inverse of each other. The one subtlety is that arch_spin_value_unlocked() takes the lock by value, rather than as a pointer, which is important for the lockref code. On the other hand arch_spin_is_locked() doesn't really care, so implement it in terms of arch_spin_value_unlocked(). Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/spinlock.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/include/asm/spinlock.h') diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 5162f8cd18c0..a30ef6999d66 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -28,8 +28,6 @@ #include #include -#define arch_spin_is_locked(x) ((x)->slock != 0) - #ifdef CONFIG_PPC64 /* use 0x800000yy when locked, where yy == CPU number */ #ifdef __BIG_ENDIAN__ @@ -59,6 +57,11 @@ static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) return lock.slock == 0; } +static inline int arch_spin_is_locked(arch_spinlock_t *lock) +{ + return !arch_spin_value_unlocked(*lock); +} + /* * This returns the old value in the lock, so we succeeded * in getting the lock if the return value is 0. -- cgit