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/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/powerpc/Kconfig') diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index fa395179ddd6..6ca5d5cabeb1 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -139,6 +139,7 @@ config PPC select OLD_SIGACTION if PPC32 select HAVE_DEBUG_STACKOVERFLOW select HAVE_IRQ_EXIT_ON_IRQ_STACK + select ARCH_USE_CMPXCHG_LOCKREF if PPC64 config GENERIC_CSUM def_bool CPU_LITTLE_ENDIAN -- cgit v1.2.3