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| author | Will Deacon <will.deacon@arm.com> | 2015-05-29 12:31:10 (GMT) |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 14:28:53 (GMT) |
| commit | 0ea366f5e1b6413a6095dce60ea49ae51e468b61 (patch) | |
| tree | fce4fc690edf16784d21a714415a74a8ce53eb2b /arch/arm64/include/asm/futex.h | |
| parent | a82e62382fcbbf5c3348e802af73583e0cac39c0 (diff) | |
| download | linux-0ea366f5e1b6413a6095dce60ea49ae51e468b61.tar.xz | |
arm64: atomics: prefetch the destination word for write prior to stxr
The cost of changing a cacheline from shared to exclusive state can be
significant, especially when this is triggered by an exclusive store,
since it may result in having to retry the transaction.
This patch makes use of prfm to prefetch cachelines for write prior to
ldxr/stxr loops when using the ll/sc atomic routines.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/futex.h')
| -rw-r--r-- | arch/arm64/include/asm/futex.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index 775e85b..007a69f 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -30,6 +30,7 @@ asm volatile( \ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ +" prfm pstl1strm, %2\n" \ "1: ldxr %w1, %2\n" \ insn "\n" \ "2: stlxr %w3, %w0, %2\n" \ @@ -120,6 +121,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, return -EFAULT; asm volatile("// futex_atomic_cmpxchg_inatomic\n" +" prfm pstl1strm, %2\n" "1: ldxr %w1, %2\n" " sub %w3, %w1, %w4\n" " cbnz %w3, 3f\n" |