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| author | Peter Zijlstra <peterz@infradead.org> | 2019-02-27 13:09:56 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-06-17 13:43:44 +0300 |
| commit | 2234a6d3a28a971182cc91d5679e444516421de0 (patch) | |
| tree | bea8d20799cc102fe565c3c1c5ccc69802c7bbf6 | |
| parent | 8dc2d993cf1aea578d947e34ea2d5c6ffd1644e4 (diff) | |
| download | linux-2234a6d3a28a971182cc91d5679e444516421de0.tar.xz | |
x86/percpu: Optimize raw_cpu_xchg()
Since raw_cpu_xchg() doesn't need to be IRQ-safe, like
this_cpu_xchg(), we can use a simple load-store instead of the cmpxchg
loop.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/percpu.h | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index f75ccccd71aa..2278797c769d 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -407,9 +407,21 @@ do { \ #define raw_cpu_or_1(pcp, val) percpu_to_op(, "or", (pcp), val) #define raw_cpu_or_2(pcp, val) percpu_to_op(, "or", (pcp), val) #define raw_cpu_or_4(pcp, val) percpu_to_op(, "or", (pcp), val) -#define raw_cpu_xchg_1(pcp, val) percpu_xchg_op(, pcp, val) -#define raw_cpu_xchg_2(pcp, val) percpu_xchg_op(, pcp, val) -#define raw_cpu_xchg_4(pcp, val) percpu_xchg_op(, pcp, val) + +/* + * raw_cpu_xchg() can use a load-store since it is not required to be + * IRQ-safe. + */ +#define raw_percpu_xchg_op(var, nval) \ +({ \ + typeof(var) pxo_ret__ = raw_cpu_read(var); \ + raw_cpu_write(var, (nval)); \ + pxo_ret__; \ +}) + +#define raw_cpu_xchg_1(pcp, val) raw_percpu_xchg_op(pcp, val) +#define raw_cpu_xchg_2(pcp, val) raw_percpu_xchg_op(pcp, val) +#define raw_cpu_xchg_4(pcp, val) raw_percpu_xchg_op(pcp, val) #define this_cpu_read_1(pcp) percpu_from_op(volatile, "mov", pcp) #define this_cpu_read_2(pcp) percpu_from_op(volatile, "mov", pcp) @@ -472,7 +484,7 @@ do { \ #define raw_cpu_and_8(pcp, val) percpu_to_op(, "and", (pcp), val) #define raw_cpu_or_8(pcp, val) percpu_to_op(, "or", (pcp), val) #define raw_cpu_add_return_8(pcp, val) percpu_add_return_op(, pcp, val) -#define raw_cpu_xchg_8(pcp, nval) percpu_xchg_op(, pcp, nval) +#define raw_cpu_xchg_8(pcp, nval) raw_percpu_xchg_op(pcp, nval) #define raw_cpu_cmpxchg_8(pcp, oval, nval) percpu_cmpxchg_op(, pcp, oval, nval) #define this_cpu_read_8(pcp) percpu_from_op(volatile, "mov", pcp) |