LXR linux/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 */
  15extern unsigned long long notrace sched_clock(void);
  16
  17/*
  18 * See the comment in kernel/sched/clock.c
  19 */
  20extern u64 running_clock(void);
  21extern u64 sched_clock_cpu(int cpu);
  22
  23
  24extern void sched_clock_init(void);
  25
  26#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
  27static inline void sched_clock_tick(void)
  28{
  29}
  30
  31static inline void clear_sched_clock_stable(void)
  32{
  33}
  34
  35static inline void sched_clock_idle_sleep_event(void)
  36{
  37}
  38
  39static inline void sched_clock_idle_wakeup_event(void)
  40{
  41}
  42
  43static inline u64 cpu_clock(int cpu)
  44{
  45        return sched_clock();
  46}
  47
  48static inline u64 local_clock(void)
  49{
  50        return sched_clock();
  51}
  52#else
  53extern int sched_clock_stable(void);
  54extern 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 */
  60extern u64 __sched_clock_offset;
  61
  62extern void sched_clock_tick(void);
  63extern void sched_clock_tick_stable(void);
  64extern void sched_clock_idle_sleep_event(void);
  65extern 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 */
  77static inline u64 cpu_clock(int cpu)
  78{
  79        return sched_clock_cpu(cpu);
  80}
  81
  82static 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 */
  94extern void enable_sched_clock_irqtime(void);
  95extern void disable_sched_clock_irqtime(void);
  96#else
  97static inline void enable_sched_clock_irqtime(void) {}
  98static inline void disable_sched_clock_irqtime(void) {}
  99#endif
 100
 101#endif /* _LINUX_SCHED_CLOCK_H */
 102