diff options
| author | Will Deacon <will.deacon@arm.com> | 2014-02-21 20:01:48 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-02-25 15:30:20 +0400 |
| commit | c32ffce0f66e5d1d4856254516e24f5ef275cd00 (patch) | |
| tree | 125229cdd38bfd6e7e62cff7eb8771a34cc999a7 /arch/arm/include/asm/atomic.h | |
| parent | 6ea41c80115f49e7d8b80312ffc99973d283471f (diff) | |
| download | linux-c32ffce0f66e5d1d4856254516e24f5ef275cd00.tar.xz | |
ARM: 7984/1: prefetch: add prefetchw invocations for barriered atomics
After a bunch of benchmarking on the interaction between dmb and pldw,
it turns out that issuing the pldw *after* the dmb instruction can
give modest performance gains (~3% atomic_add_return improvement on a
dual A15).
This patch adds prefetchw invocations to our barriered atomic operations
including cmpxchg, test_and_xxx and futexes.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/atomic.h')
| -rw-r--r-- | arch/arm/include/asm/atomic.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h index 62d2cb53b069..6e410090896e 100644 --- a/arch/arm/include/asm/atomic.h +++ b/arch/arm/include/asm/atomic.h @@ -60,6 +60,7 @@ static inline int atomic_add_return(int i, atomic_t *v) int result; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic_add_return\n" "1: ldrex %0, [%3]\n" @@ -99,6 +100,7 @@ static inline int atomic_sub_return(int i, atomic_t *v) int result; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic_sub_return\n" "1: ldrex %0, [%3]\n" @@ -121,6 +123,7 @@ static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new) unsigned long res; smp_mb(); + prefetchw(&ptr->counter); do { __asm__ __volatile__("@ atomic_cmpxchg\n" @@ -299,6 +302,7 @@ static inline long long atomic64_add_return(long long i, atomic64_t *v) unsigned long tmp; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic64_add_return\n" "1: ldrexd %0, %H0, [%3]\n" @@ -340,6 +344,7 @@ static inline long long atomic64_sub_return(long long i, atomic64_t *v) unsigned long tmp; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic64_sub_return\n" "1: ldrexd %0, %H0, [%3]\n" @@ -364,6 +369,7 @@ static inline long long atomic64_cmpxchg(atomic64_t *ptr, long long old, unsigned long res; smp_mb(); + prefetchw(&ptr->counter); do { __asm__ __volatile__("@ atomic64_cmpxchg\n" @@ -388,6 +394,7 @@ static inline long long atomic64_xchg(atomic64_t *ptr, long long new) unsigned long tmp; smp_mb(); + prefetchw(&ptr->counter); __asm__ __volatile__("@ atomic64_xchg\n" "1: ldrexd %0, %H0, [%3]\n" @@ -409,6 +416,7 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v) unsigned long tmp; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic64_dec_if_positive\n" "1: ldrexd %0, %H0, [%3]\n" @@ -436,6 +444,7 @@ static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u) int ret = 1; smp_mb(); + prefetchw(&v->counter); __asm__ __volatile__("@ atomic64_add_unless\n" "1: ldrexd %0, %H0, [%4]\n" |