diff options
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 124 |
1 files changed, 108 insertions, 16 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index e8dfa6f0d843..6cc0df970f1a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -177,9 +177,11 @@ extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load); extern void calc_global_load(unsigned long ticks); #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) -extern void update_cpu_load_nohz(int active); +extern void cpu_load_update_nohz_start(void); +extern void cpu_load_update_nohz_stop(void); #else -static inline void update_cpu_load_nohz(int active) { } +static inline void cpu_load_update_nohz_start(void) { } +static inline void cpu_load_update_nohz_stop(void) { } #endif extern void dump_cpu_task(int cpu); @@ -371,6 +373,15 @@ extern void cpu_init (void); extern void trap_init(void); extern void update_process_times(int user); extern void scheduler_tick(void); +extern int sched_cpu_starting(unsigned int cpu); +extern int sched_cpu_activate(unsigned int cpu); +extern int sched_cpu_deactivate(unsigned int cpu); + +#ifdef CONFIG_HOTPLUG_CPU +extern int sched_cpu_dying(unsigned int cpu); +#else +# define sched_cpu_dying NULL +#endif extern void sched_show_task(struct task_struct *p); @@ -934,9 +945,19 @@ enum cpu_idle_type { }; /* + * Integer metrics need fixed point arithmetic, e.g., sched/fair + * has a few: load, load_avg, util_avg, freq, and capacity. + * + * We define a basic fixed point arithmetic range, and then formalize + * all these metrics based on that basic range. + */ +# define SCHED_FIXEDPOINT_SHIFT 10 +# define SCHED_FIXEDPOINT_SCALE (1L << SCHED_FIXEDPOINT_SHIFT) + +/* * Increase resolution of cpu_capacity calculations */ -#define SCHED_CAPACITY_SHIFT 10 +#define SCHED_CAPACITY_SHIFT SCHED_FIXEDPOINT_SHIFT #define SCHED_CAPACITY_SCALE (1L << SCHED_CAPACITY_SHIFT) /* @@ -1198,18 +1219,56 @@ struct load_weight { }; /* - * The load_avg/util_avg accumulates an infinite geometric series. - * 1) load_avg factors frequency scaling into the amount of time that a - * sched_entity is runnable on a rq into its weight. For cfs_rq, it is the - * aggregated such weights of all runnable and blocked sched_entities. - * 2) util_avg factors frequency and cpu scaling into the amount of time - * that a sched_entity is running on a CPU, in the range [0..SCHED_LOAD_SCALE]. - * For cfs_rq, it is the aggregated such times of all runnable and + * The load_avg/util_avg accumulates an infinite geometric series + * (see __update_load_avg() in kernel/sched/fair.c). + * + * [load_avg definition] + * + * load_avg = runnable% * scale_load_down(load) + * + * where runnable% is the time ratio that a sched_entity is runnable. + * For cfs_rq, it is the aggregated load_avg of all runnable and * blocked sched_entities. - * The 64 bit load_sum can: - * 1) for cfs_rq, afford 4353082796 (=2^64/47742/88761) entities with - * the highest weight (=88761) always runnable, we should not overflow - * 2) for entity, support any load.weight always runnable + * + * load_avg may also take frequency scaling into account: + * + * load_avg = runnable% * scale_load_down(load) * freq% + * + * where freq% is the CPU frequency normalized to the highest frequency. + * + * [util_avg definition] + * + * util_avg = running% * SCHED_CAPACITY_SCALE + * + * where running% is the time ratio that a sched_entity is running on + * a CPU. For cfs_rq, it is the aggregated util_avg of all runnable + * and blocked sched_entities. + * + * util_avg may also factor frequency scaling and CPU capacity scaling: + * + * util_avg = running% * SCHED_CAPACITY_SCALE * freq% * capacity% + * + * where freq% is the same as above, and capacity% is the CPU capacity + * normalized to the greatest capacity (due to uarch differences, etc). + * + * N.B., the above ratios (runnable%, running%, freq%, and capacity%) + * themselves are in the range of [0, 1]. To do fixed point arithmetics, + * we therefore scale them to as large a range as necessary. This is for + * example reflected by util_avg's SCHED_CAPACITY_SCALE. + * + * [Overflow issue] + * + * The 64-bit load_sum can have 4353082796 (=2^64/47742/88761) entities + * with the highest load (=88761), always runnable on a single cfs_rq, + * and should not overflow as the number already hits PID_MAX_LIMIT. + * + * For all other cases (including 32-bit kernels), struct load_weight's + * weight will overflow first before we do, because: + * + * Max(load_avg) <= Max(load.weight) + * + * Then it is the load_weight's responsibility to consider overflow + * issues. */ struct sched_avg { u64 last_update_time, load_sum; @@ -1871,6 +1930,11 @@ extern int arch_task_struct_size __read_mostly; /* Future-safe accessor for struct task_struct's cpus_allowed. */ #define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed) +static inline int tsk_nr_cpus_allowed(struct task_struct *p) +{ + return p->nr_cpus_allowed; +} + #define TNF_MIGRATED 0x01 #define TNF_NO_GROUP 0x02 #define TNF_SHARED 0x04 @@ -2303,8 +2367,6 @@ extern unsigned long long notrace sched_clock(void); /* * See the comment in kernel/sched/clock.c */ -extern u64 cpu_clock(int cpu); -extern u64 local_clock(void); extern u64 running_clock(void); extern u64 sched_clock_cpu(int cpu); @@ -2323,6 +2385,16 @@ static inline void sched_clock_idle_sleep_event(void) static inline void sched_clock_idle_wakeup_event(u64 delta_ns) { } + +static inline u64 cpu_clock(int cpu) +{ + return sched_clock(); +} + +static inline u64 local_clock(void) +{ + return sched_clock(); +} #else /* * Architectures can set this to 1 if they have specified @@ -2337,6 +2409,26 @@ extern void clear_sched_clock_stable(void); extern void sched_clock_tick(void); extern void sched_clock_idle_sleep_event(void); extern void sched_clock_idle_wakeup_event(u64 delta_ns); + +/* + * As outlined in clock.c, provides a fast, high resolution, nanosecond + * time source that is monotonic per cpu argument and has bounded drift + * between cpus. + * + * ######################### BIG FAT WARNING ########################## + * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can # + * # go backwards !! # + * #################################################################### + */ +static inline u64 cpu_clock(int cpu) +{ + return sched_clock_cpu(cpu); +} + +static inline u64 local_clock(void) +{ + return sched_clock_cpu(raw_smp_processor_id()); +} #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING |