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| author | Steve Capper | 2014-10-24 14:22:20 +0200 |
|---|---|---|
| committer | Will Deacon | 2014-11-06 18:25:28 +0100 |
| commit | 5284e1b4bc8ae6fcc1c92c63cf6c876a53292f82 (patch) | |
| tree | 3aeddebd2c9ebbb59bf7e6eec64796c97c5c5c2c /arch/arm64/Kconfig | |
| parent | arm64: optimize memcpy_{from,to}io() and memset_io() (diff) | |
| download | kernel-qcow2-linux-5284e1b4bc8ae6fcc1c92c63cf6c876a53292f82.tar.gz kernel-qcow2-linux-5284e1b4bc8ae6fcc1c92c63cf6c876a53292f82.tar.xz kernel-qcow2-linux-5284e1b4bc8ae6fcc1c92c63cf6c876a53292f82.zip | |
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/Kconfig | 2 |
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 |