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| author | David S. Miller <davem@davemloft.net> | 2012-10-28 07:00:41 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-10-28 07:00:41 +0100 |
| commit | e9b9eb59ffcdee09ec96b040f85c919618f4043e (patch) | |
| tree | 30f93cc20aa577ec5b12f609641fdf84d0bd5124 /arch/sparc/include/asm/processor_64.h | |
| parent | sparc64: Fix cpu strand yielding. (diff) | |
| download | linux-e9b9eb59ffcdee09ec96b040f85c919618f4043e.tar.xz linux-e9b9eb59ffcdee09ec96b040f85c919618f4043e.zip | |
sparc64: Use pause instruction when available.
In atomic backoff and cpu_relax(), use the pause instruction
found on SPARC-T4 and later.
It makes the cpu strand unselectable for the given number of
cycles, unless an intervening disrupting trap occurs.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/include/asm/processor_64.h')
| -rw-r--r-- | arch/sparc/include/asm/processor_64.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/sparc/include/asm/processor_64.h b/arch/sparc/include/asm/processor_64.h index 986563409469..9cdf52eec48a 100644 --- a/arch/sparc/include/asm/processor_64.h +++ b/arch/sparc/include/asm/processor_64.h @@ -196,9 +196,16 @@ extern unsigned long get_wchan(struct task_struct *task); #define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc) #define KSTK_ESP(tsk) (task_pt_regs(tsk)->u_regs[UREG_FP]) -#define cpu_relax() asm volatile("rd %%ccr, %%g0\n\t" \ - "rd %%ccr, %%g0\n\t" \ - "rd %%ccr, %%g0" \ +#define cpu_relax() asm volatile("\n99:\n\t" \ + "rd %%ccr, %%g0\n\t" \ + "rd %%ccr, %%g0\n\t" \ + "rd %%ccr, %%g0\n\t" \ + ".section .pause_patch,\"ax\"\n\t"\ + ".word 99b\n\t" \ + "wr %%g0, 128, %%asr27\n\t" \ + "nop\n\t" \ + "nop\n\t" \ + ".previous" \ ::: "memory") /* Prefetch support. This is tuned for UltraSPARC-III and later. |