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| author | Ingo Molnar | 2009-01-15 14:15:53 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2009-01-16 14:20:31 +0100 |
| commit | 6dbde3530850d4d8bfc1b6bd4006d92786a2787f (patch) | |
| tree | 08c6dd55e860827311b889e2ecfe3de9f51421a0 /arch/x86/include/asm/pda.h | |
| parent | x86: misc clean up after the percpu update (diff) | |
| download | kernel-qcow2-linux-6dbde3530850d4d8bfc1b6bd4006d92786a2787f.tar.gz kernel-qcow2-linux-6dbde3530850d4d8bfc1b6bd4006d92786a2787f.tar.xz kernel-qcow2-linux-6dbde3530850d4d8bfc1b6bd4006d92786a2787f.zip | |
percpu: add optimized generic percpu accessors
It is an optimization and a cleanup, and adds the following new
generic percpu methods:
percpu_read()
percpu_write()
percpu_add()
percpu_sub()
percpu_and()
percpu_or()
percpu_xor()
and implements support for them on x86. (other architectures will fall
back to a default implementation)
The advantage is that for example to read a local percpu variable,
instead of this sequence:
return __get_cpu_var(var);
ffffffff8102ca2b: 48 8b 14 fd 80 09 74 mov -0x7e8bf680(,%rdi,8),%rdx
ffffffff8102ca32: 81
ffffffff8102ca33: 48 c7 c0 d8 59 00 00 mov $0x59d8,%rax
ffffffff8102ca3a: 48 8b 04 10 mov (%rax,%rdx,1),%rax
We can get a single instruction by using the optimized variants:
return percpu_read(var);
ffffffff8102ca3f: 65 48 8b 05 91 8f fd mov %gs:0x7efd8f91(%rip),%rax
I also cleaned up the x86-specific APIs and made the x86 code use
these new generic percpu primitives.
tj: * fixed generic percpu_sub() definition as Roel Kluin pointed out
* added percpu_and() for completeness's sake
* made generic percpu ops atomic against preemption
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/pda.h')
| -rw-r--r-- | arch/x86/include/asm/pda.h | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h index e3d3a081d798..47f274fe6953 100644 --- a/arch/x86/include/asm/pda.h +++ b/arch/x86/include/asm/pda.h @@ -45,11 +45,11 @@ extern void pda_init(int); #define cpu_pda(cpu) (&per_cpu(__pda, cpu)) -#define read_pda(field) x86_read_percpu(__pda.field) -#define write_pda(field, val) x86_write_percpu(__pda.field, val) -#define add_pda(field, val) x86_add_percpu(__pda.field, val) -#define sub_pda(field, val) x86_sub_percpu(__pda.field, val) -#define or_pda(field, val) x86_or_percpu(__pda.field, val) +#define read_pda(field) percpu_read(__pda.field) +#define write_pda(field, val) percpu_write(__pda.field, val) +#define add_pda(field, val) percpu_add(__pda.field, val) +#define sub_pda(field, val) percpu_sub(__pda.field, val) +#define or_pda(field, val) percpu_or(__pda.field, val) /* This is not atomic against other CPUs -- CPU preemption needs to be off */ #define test_and_clear_bit_pda(bit, field) \ |