diff options
| -rw-r--r-- | share/man/man9/arch.9 | 7 | ||||
| -rw-r--r-- | sys/include/arch/amd64/cpu.h | 7 | ||||
| -rw-r--r-- | sys/kern/kern_sched.c | 8 |
3 files changed, 16 insertions, 6 deletions
diff --git a/share/man/man9/arch.9 b/share/man/man9/arch.9 index 3285208..adbc437 100644 --- a/share/man/man9/arch.9 +++ b/share/man/man9/arch.9 @@ -95,6 +95,13 @@ The macro calls an internal function that fetches the cpu_info structure for the BSP. +The macro +.Ft hint_spinwait() +hints the processor that it is currently +in a spin-wait loop. This greatly reduces the +processor’s power consumption and improves +the performance of the spin-wait loop. + The function these macros call must return a pointer to a .Ft cpu_info diff --git a/sys/include/arch/amd64/cpu.h b/sys/include/arch/amd64/cpu.h index c72c106..e6f2de0 100644 --- a/sys/include/arch/amd64/cpu.h +++ b/sys/include/arch/amd64/cpu.h @@ -37,6 +37,13 @@ #include <sys/queue.h> #include <machine/tss.h> #include <machine/msr.h> +/* + * XXX: We are not using the PAUSE instruction for the sake of + * ensuring compatibility... PAUSE is F3 90, REP NOP is + * F3 90... REP NOP will be read as a PAUSE on processors + * that support it. + */ +#define hint_spinwait() __ASMV("rep; nop") #define this_cpu() amd64_this_cpu() #define get_bsp() amd64_get_bsp() diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c index da4c6c5..4f17ddf 100644 --- a/sys/kern/kern_sched.c +++ b/sys/kern/kern_sched.c @@ -32,6 +32,7 @@ #include <sys/types.h> #include <sys/cdefs.h> #include <sys/spinlock.h> +#include <machine/cpu.h> #include <assert.h> /* @@ -59,17 +60,12 @@ sched_enqueue_ci(struct cpu_info *ci) /* * Processor awaiting tasks to be assigned will be here spinning. - * - * XXX: We are not using the PAUSE instruction for the sake of - * ensuring compatibility... PAUSE is F3 90, REP NOP is - * F3 90... REP NOP will be read as a PAUSE on processors - * that support it. */ __noreturn static void sched_enter(void) { for (;;) { - __ASMV("rep; nop"); + hint_spinwait(); } } |