include/linux/sched/clock.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SCHED_CLOCK_H
   3 #define _LINUX_SCHED_CLOCK_H
   4
   5 #include <linux/smp.h>
   6
   7 /*
   8  * Do not use outside of architecture code which knows its limitations.
   9  *
  10  * sched_clock() has no promise of monotonicity or bounded drift between
  11  * CPUs, use (which you should not) requires disabling IRQs.
  12  *
  13  * Please use one of the three interfaces below.
  14  */
  15 extern unsigned long long notrace sched_clock(void);
  16
  17 /*
  18  * See the comment in kernel/sched/clock.c
  19  */
  20 extern u64 running_clock(void);
  21 extern u64 sched_clock_cpu(int cpu);
  22
  23
  24 extern void sched_clock_init(void);
  25
  26 #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
  27 static inline void sched_clock_tick(void)
  28 {
  29 }
  30
  31 static inline void clear_sched_clock_stable(void)
  32 {
  33 }
  34
  35 static inline void sched_clock_idle_sleep_event(void)
  36 {
  37 }
  38
  39 static inline void sched_clock_idle_wakeup_event(void)
  40 {
  41 }
  42
  43 static inline u64 cpu_clock(int cpu)
  44 {
  45         return sched_clock();
  46 }
  47
  48 static inline u64 local_clock(void)
  49 {
  50         return sched_clock();
  51 }
  52 #else
  53 extern int sched_clock_stable(void);
  54 extern void clear_sched_clock_stable(void);
  55
  56 /*
  57  * When sched_clock_stable(), __sched_clock_offset provides the offset
  58  * between local_clock() and sched_clock().
  59  */
  60 extern u64 __sched_clock_offset;
  61
  62 extern void sched_clock_tick(void);
  63 extern void sched_clock_tick_stable(void);
  64 extern void sched_clock_idle_sleep_event(void);
  65 extern void sched_clock_idle_wakeup_event(void);
  66
  67 /*
  68  * As outlined in clock.c, provides a fast, high resolution, nanosecond
  69  * time source that is monotonic per cpu argument and has bounded drift
  70  * between cpus.
  71  *
  72  * ######################### BIG FAT WARNING ##########################
  73  * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
  74  * # go backwards !!                                                  #
  75  * ####################################################################
  76  */
  77 static inline u64 cpu_clock(int cpu)
  78 {
  79         return sched_clock_cpu(cpu);
  80 }
  81
  82 static inline u64 local_clock(void)
  83 {
  84         return sched_clock_cpu(raw_smp_processor_id());
  85 }
  86 #endif
  87
  88 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
  89 /*
  90  * An i/f to runtime opt-in for irq time accounting based off of sched_clock.
  91  * The reason for this explicit opt-in is not to have perf penalty with
  92  * slow sched_clocks.
  93  */
  94 extern void enable_sched_clock_irqtime(void);
  95 extern void disable_sched_clock_irqtime(void);
  96 #else
  97 static inline void enable_sched_clock_irqtime(void) {}
  98 static inline void disable_sched_clock_irqtime(void) {}
  99 #endif
 100
 101 #endif /* _LINUX_SCHED_CLOCK_H */