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 u64 sched_clock(void);
  16
  17 #if defined(CONFIG_ARCH_WANTS_NO_INSTR) || defined(CONFIG_GENERIC_SCHED_CLOCK)
  18 extern u64 sched_clock_noinstr(void);
  19 #else
  20 static __always_inline u64 sched_clock_noinstr(void)
  21 {
  22         return sched_clock();
  23 }
  24 #endif
  25
  26 /*
  27  * See the comment in kernel/sched/clock.c
  28  */
  29 extern u64 running_clock(void);
  30 extern u64 sched_clock_cpu(int cpu);
  31
  32
  33 extern void sched_clock_init(void);
  34
  35 #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
  36 static inline void sched_clock_tick(void)
  37 {
  38 }
  39
  40 static inline void clear_sched_clock_stable(void)
  41 {
  42 }
  43
  44 static inline void sched_clock_idle_sleep_event(void)
  45 {
  46 }
  47
  48 static inline void sched_clock_idle_wakeup_event(void)
  49 {
  50 }
  51
  52 static inline u64 cpu_clock(int cpu)
  53 {
  54         return sched_clock();
  55 }
  56
  57 static __always_inline u64 local_clock_noinstr(void)
  58 {
  59         return sched_clock_noinstr();
  60 }
  61
  62 static __always_inline u64 local_clock(void)
  63 {
  64         return sched_clock();
  65 }
  66 #else
  67 extern int sched_clock_stable(void);
  68 extern void clear_sched_clock_stable(void);
  69
  70 /*
  71  * When sched_clock_stable(), __sched_clock_offset provides the offset
  72  * between local_clock() and sched_clock().
  73  */
  74 extern u64 __sched_clock_offset;
  75
  76 extern void sched_clock_tick(void);
  77 extern void sched_clock_tick_stable(void);
  78 extern void sched_clock_idle_sleep_event(void);
  79 extern void sched_clock_idle_wakeup_event(void);
  80
  81 /*
  82  * As outlined in clock.c, provides a fast, high resolution, nanosecond
  83  * time source that is monotonic per cpu argument and has bounded drift
  84  * between cpus.
  85  *
  86  * ######################### BIG FAT WARNING ##########################
  87  * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
  88  * # go backwards !!                                                  #
  89  * ####################################################################
  90  */
  91 static inline u64 cpu_clock(int cpu)
  92 {
  93         return sched_clock_cpu(cpu);
  94 }
  95
  96 extern u64 local_clock_noinstr(void);
  97 extern u64 local_clock(void);
  98
  99 #endif
 100
 101 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
 102 /*
 103  * An i/f to runtime opt-in for irq time accounting based off of sched_clock.
 104  * The reason for this explicit opt-in is not to have perf penalty with
 105  * slow sched_clocks.
 106  */
 107 extern void enable_sched_clock_irqtime(void);
 108 extern void disable_sched_clock_irqtime(void);
 109 #else
 110 static inline void enable_sched_clock_irqtime(void) {}
 111 static inline void disable_sched_clock_irqtime(void) {}
 112 #endif
 113
 114 #endif /* _LINUX_SCHED_CLOCK_H */