diff options
| author | Masao Uebayashi <uebayasi@cvs.openbsd.org> | 2014-07-11 10:53:08 +0000 |
|---|---|---|
| committer | Masao Uebayashi <uebayasi@cvs.openbsd.org> | 2014-07-11 10:53:08 +0000 |
| commit | 123f4b6634c6f64980c8a879dc8140fcc706d6d2 (patch) | |
| tree | 8f16526685cec43a88ad22499b7316fe46507593 /sys/arch/i386 | |
| parent | 7153f32429c8f459cac9dbed87a626718d2b84b9 (diff) | |
CPU_BUSY_CYCLE(): A new MI statement for busy loop power reduction
The new CPU_BUSY_CYCLE() may be put in a busy loop body so that CPU can reduce
power consumption, as Linux's cpu_relax() and FreeBSD's cpu_spinwait(). To
start minimally, use PAUSE on i386/amd64 and empty on others. The name is
chosen following the existing cpu_idle_*() functions. Naming and API may be
polished later.
OK kettenis@
Diffstat (limited to 'sys/arch/i386')
| -rw-r--r-- | sys/arch/i386/include/cpu.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/sys/arch/i386/include/cpu.h b/sys/arch/i386/include/cpu.h index fec9ff29642..91b558a2934 100644 --- a/sys/arch/i386/include/cpu.h +++ b/sys/arch/i386/include/cpu.h @@ -1,4 +1,4 @@ -/* $OpenBSD: cpu.h,v 1.133 2014/03/29 18:09:29 guenther Exp $ */ +/* $OpenBSD: cpu.h,v 1.134 2014/07/11 10:53:07 uebayasi Exp $ */ /* $NetBSD: cpu.h,v 1.35 1996/05/05 19:29:26 christos Exp $ */ /*- @@ -225,6 +225,8 @@ extern void cpu_init_idle_pcbs(void); void cpu_kick(struct cpu_info *); void cpu_unidle(struct cpu_info *); +#define CPU_BUSY_CYCLE() __asm volatile("pause": : : "memory") + #else /* MULTIPROCESSOR */ #define MAXCPUS 1 @@ -237,6 +239,8 @@ void cpu_unidle(struct cpu_info *); #define cpu_kick(ci) #define cpu_unidle(ci) +#define CPU_BUSY_CYCLE() do {} while (0) + #endif #define aston(p) ((p)->p_md.md_astpending = 1) |