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authorSteve Capper <steve.capper@linaro.org>2014-10-24 13:22:20 +0100
committerWill Deacon <will.deacon@arm.com>2014-11-06 17:25:28 +0000
commit5284e1b4bc8ae6fcc1c92c63cf6c876a53292f82 (patch)
tree3aeddebd2c9ebbb59bf7e6eec64796c97c5c5c2c /arch/arm64/Kconfig
parent70ddb63a88bfd45eb6abe36e2bf4f8f351a447d7 (diff)
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arm64: xchg: Implement cmpxchg_double
The arm64 architecture has the ability to exclusively load and store a pair of registers from an address (ldxp/stxp). Also the SLUB can take advantage of a cmpxchg_double implementation to avoid taking some locks. This patch provides an implementation of cmpxchg_double for 64-bit pairs, and activates the logic required for the SLUB to use these functions (HAVE_ALIGNED_STRUCT_PAGE and HAVE_CMPXCHG_DOUBLE). Also definitions of this_cpu_cmpxchg_8 and this_cpu_cmpxchg_double_8 are wired up to cmpxchg_local and cmpxchg_double_local (rather than the stock implementations that perform non-atomic operations with interrupts disabled) as they are used by the SLUB. On a Juno platform running on only the A57s I get quite a noticeable performance improvement with 5 runs of hackbench on v3.17: Baseline | With Patch -----------------+----------- Mean 119.2312 | 106.1782 StdDev 0.4919 | 0.4494 (times taken to complete `./hackbench 100 process 1000', in seconds) Signed-off-by: Steve Capper <steve.capper@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
-rw-r--r--arch/arm64/Kconfig2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2c3c2ca6f8bc..1e0e4671dd25 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -34,6 +34,7 @@ config ARM64
select GENERIC_TIME_VSYSCALL
select HANDLE_DOMAIN_IRQ
select HARDIRQS_SW_RESEND
+ select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KGDB
@@ -41,6 +42,7 @@ config ARM64
select HAVE_BPF_JIT
select HAVE_C_RECORDMCOUNT
select HAVE_CC_STACKPROTECTOR
+ select HAVE_CMPXCHG_DOUBLE
select HAVE_DEBUG_BUGVERBOSE
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_API_DEBUG