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authorMichael Ellerman <mpe@ellerman.id.au>2014-01-15 02:14:28 -0500
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-01-27 22:45:43 -0500
commit3405d230b374b6923878b21b8d708d7db1f734ef (patch)
tree789bd76b9c2b5a0f00bbe1f410927cf23debf96d /arch/powerpc/Kconfig
parentf7d98d18a01ece2863984d4fb5ae949b18b02715 (diff)
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 <mpe@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/Kconfig')
-rw-r--r--arch/powerpc/Kconfig1
1 files changed, 1 insertions, 0 deletions
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
139 select OLD_SIGACTION if PPC32 139 select OLD_SIGACTION if PPC32
140 select HAVE_DEBUG_STACKOVERFLOW 140 select HAVE_DEBUG_STACKOVERFLOW
141 select HAVE_IRQ_EXIT_ON_IRQ_STACK 141 select HAVE_IRQ_EXIT_ON_IRQ_STACK
142 select ARCH_USE_CMPXCHG_LOCKREF if PPC64
142 143
143config GENERIC_CSUM 144config GENERIC_CSUM
144 def_bool CPU_LITTLE_ENDIAN 145 def_bool CPU_LITTLE_ENDIAN