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| author | David S. Miller <davem@davemloft.net> | 2012-10-28 10:00:41 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-10-28 10:00:41 +0400 |
| commit | e9b9eb59ffcdee09ec96b040f85c919618f4043e (patch) | |
| tree | 30f93cc20aa577ec5b12f609641fdf84d0bd5124 /arch/sparc/include/asm/backoff.h | |
| parent | 270c10e00a1e557e068803a22e0556281ceb1830 (diff) | |
| download | linux-e9b9eb59ffcdee09ec96b040f85c919618f4043e.tar.xz | |
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/backoff.h')
| -rw-r--r-- | arch/sparc/include/asm/backoff.h | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/arch/sparc/include/asm/backoff.h b/arch/sparc/include/asm/backoff.h index 64b077b3b13b..20f01df0871b 100644 --- a/arch/sparc/include/asm/backoff.h +++ b/arch/sparc/include/asm/backoff.h @@ -11,19 +11,25 @@ #define BACKOFF_LABEL(spin_label, continue_label) \ spin_label -#define BACKOFF_SPIN(reg, tmp, label) \ - mov reg, tmp; \ -88: rd %ccr, %g0; \ - rd %ccr, %g0; \ - rd %ccr, %g0; \ - brnz,pt tmp, 88b; \ - sub tmp, 1, tmp; \ - set BACKOFF_LIMIT, tmp; \ - cmp reg, tmp; \ - bg,pn %xcc, label; \ - nop; \ - ba,pt %xcc, label; \ - sllx reg, 1, reg; +#define BACKOFF_SPIN(reg, tmp, label) \ + mov reg, tmp; \ +88: rd %ccr, %g0; \ + rd %ccr, %g0; \ + rd %ccr, %g0; \ + .section .pause_patch,"ax"; \ + .word 88b; \ + sllx tmp, 7, tmp; \ + wr tmp, 0, %asr27; \ + clr tmp; \ + .previous; \ + brnz,pt tmp, 88b; \ + sub tmp, 1, tmp; \ + set BACKOFF_LIMIT, tmp; \ + cmp reg, tmp; \ + bg,pn %xcc, label; \ + nop; \ + ba,pt %xcc, label; \ + sllx reg, 1, reg; #else |