diff options
Diffstat (limited to 'include/asm-i386')
| -rw-r--r-- | include/asm-i386/paravirt.h | 7 | ||||
| -rw-r--r-- | include/asm-i386/timer.h | 32 | ||||
| -rw-r--r-- | include/asm-i386/vmi_time.h | 2 |
3 files changed, 37 insertions, 4 deletions
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h index 690ada2..7df88be 100644 --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -118,7 +118,7 @@ struct paravirt_ops u64 (*read_tsc)(void); u64 (*read_pmc)(void); - u64 (*get_scheduled_cycles)(void); + unsigned long long (*sched_clock)(void); unsigned long (*get_cpu_khz)(void); /* Segment descriptor handling */ @@ -566,7 +566,10 @@ static inline u64 paravirt_read_tsc(void) #define rdtscll(val) (val = paravirt_read_tsc()) -#define get_scheduled_cycles(val) (val = paravirt_ops.get_scheduled_cycles()) +static inline unsigned long long paravirt_sched_clock(void) +{ + return PVOP_CALL0(unsigned long long, sched_clock); +} #define calculate_cpu_khz() (paravirt_ops.get_cpu_khz()) #define write_tsc(val1,val2) wrmsr(0x10, val1, val2) diff --git a/include/asm-i386/timer.h b/include/asm-i386/timer.h index 153770e..51a713e 100644 --- a/include/asm-i386/timer.h +++ b/include/asm-i386/timer.h @@ -15,8 +15,38 @@ extern int no_sync_cmos_clock; extern int recalibrate_cpu_khz(void); #ifndef CONFIG_PARAVIRT -#define get_scheduled_cycles(val) rdtscll(val) #define calculate_cpu_khz() native_calculate_cpu_khz() #endif +/* Accellerators for sched_clock() + * convert from cycles(64bits) => nanoseconds (64bits) + * basic equation: + * ns = cycles / (freq / ns_per_sec) + * ns = cycles * (ns_per_sec / freq) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) + * + * Then we use scaling math (suggested by george@mvista.com) to get: + * ns = cycles * (10^6 * SC / cpu_khz) / SC + * ns = cycles * cyc2ns_scale / SC + * + * And since SC is a constant power of two, we can convert the div + * into a shift. + * + * We can use khz divisor instead of mhz to keep a better percision, since + * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. + * (mathieu.desnoyers@polymtl.ca) + * + * -johnstul@us.ibm.com "math is hard, lets go shopping!" + */ +extern unsigned long cyc2ns_scale __read_mostly; + +#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ + +static inline unsigned long long cycles_2_ns(unsigned long long cyc) +{ + return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; +} + + #endif diff --git a/include/asm-i386/vmi_time.h b/include/asm-i386/vmi_time.h index 213930b..4781881 100644 --- a/include/asm-i386/vmi_time.h +++ b/include/asm-i386/vmi_time.h @@ -49,7 +49,7 @@ extern struct vmi_timer_ops { extern void __init vmi_time_init(void); extern unsigned long vmi_get_wallclock(void); extern int vmi_set_wallclock(unsigned long now); -extern unsigned long long vmi_get_sched_cycles(void); +extern unsigned long long vmi_sched_clock(void); extern unsigned long vmi_cpu_khz(void); #ifdef CONFIG_X86_LOCAL_APIC |