linux/arch/x86/xen
Ingo Molnar 6dbde35308 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>
2009-01-16 14:20:31 +01:00
..
debugfs.c
debugfs.h
enlighten.c percpu: add optimized generic percpu accessors 2009-01-16 14:20:31 +01:00
grant-table.c
irq.c percpu: add optimized generic percpu accessors 2009-01-16 14:20:31 +01:00
Kconfig
Makefile ftrace: rename FTRACE to FUNCTION_TRACER 2008-10-20 18:27:03 +02:00
mmu.c percpu: add optimized generic percpu accessors 2009-01-16 14:20:31 +01:00
mmu.h
multicalls.c xen: whitespace/checkpatch cleanup 2008-12-16 21:05:01 +01:00
multicalls.h percpu: add optimized generic percpu accessors 2009-01-16 14:20:31 +01:00
setup.c xen: whitespace/checkpatch cleanup 2008-12-16 21:05:01 +01:00
smp.c percpu: add optimized generic percpu accessors 2009-01-16 14:20:31 +01:00
spinlock.c genirq: revert dynarray 2008-10-16 16:53:15 +02:00
suspend.c xen: convert to cpumask_var_t and new cpumask primitives. 2008-12-16 17:40:57 -08:00
time.c Merge branch 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6 2009-01-03 11:56:24 -08:00
vdso.h
xen-asm_32.S
xen-asm_64.S
xen-head.S
xen-ops.h xen: convert to cpumask_var_t and new cpumask primitives. 2008-12-16 17:40:57 -08:00