path: root/arch/arm/lib
diff options
authorWill Deacon <will.deacon@arm.com>2014-02-21 17:01:48 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-02-25 11:30:20 +0000
commitc32ffce0f66e5d1d4856254516e24f5ef275cd00 (patch)
tree125229cdd38bfd6e7e62cff7eb8771a34cc999a7 /arch/arm/lib
parent6ea41c80115f49e7d8b80312ffc99973d283471f (diff)
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/lib')
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm/lib/bitops.h b/arch/arm/lib/bitops.h
index 52886b89706c..9f12ed1eea86 100644
--- a/arch/arm/lib/bitops.h
+++ b/arch/arm/lib/bitops.h
@@ -37,6 +37,11 @@ UNWIND( .fnstart )
add r1, r1, r0, lsl #2 @ Get word offset
mov r3, r2, lsl r3 @ create mask
+#if __LINUX_ARM_ARCH__ >= 7 && defined(CONFIG_SMP)
+ .arch_extension mp
+ ALT_SMP(W(pldw) [r1])
+ ALT_UP(W(nop))
1: ldrex r2, [r1]
ands r0, r2, r3 @ save old value of bit
\instr r2, r2, r3 @ toggle bit