Messages in this thread Patch in this message | | | Date | Tue, 23 Nov 2010 17:51:46 -0600 | From | Christoph Lameter <> | Subject | [thiscpuops upgrade 07/10] highmem: Use this_cpu_xx_return() operations |
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Use this_cpu operations to optimize access primitives for highmem.
The main effect is the avoidance of address calculations through the use of a segment prefix.
Signed-off-by: Christoph Lameter <cl@linux.com>
--- include/linux/highmem.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
Index: linux-2.6/include/linux/highmem.h =================================================================== --- linux-2.6.orig/include/linux/highmem.h 2010-11-22 14:43:40.000000000 -0600 +++ linux-2.6/include/linux/highmem.h 2010-11-22 14:45:02.000000000 -0600 @@ -81,7 +81,8 @@ DECLARE_PER_CPU(int, __kmap_atomic_idx); static inline int kmap_atomic_idx_push(void) { - int idx = __get_cpu_var(__kmap_atomic_idx)++; + int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1; + #ifdef CONFIG_DEBUG_HIGHMEM WARN_ON_ONCE(in_irq() && !irqs_disabled()); BUG_ON(idx > KM_TYPE_NR); @@ -91,12 +92,12 @@ static inline int kmap_atomic_idx_push(v static inline int kmap_atomic_idx(void) { - return __get_cpu_var(__kmap_atomic_idx) - 1; + return __this_cpu_read(__kmap_atomic_idx) - 1; } static inline int kmap_atomic_idx_pop(void) { - int idx = --__get_cpu_var(__kmap_atomic_idx); + int idx = __this_cpu_dec_return(__kmap_atomic_idx); #ifdef CONFIG_DEBUG_HIGHMEM BUG_ON(idx < 0); #endif
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