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 u64 sched_clock(void);
 16
 17#if defined(CONFIG_ARCH_WANTS_NO_INSTR) || defined(CONFIG_GENERIC_SCHED_CLOCK)
 18extern u64 sched_clock_noinstr(void);
 19#else
 20static __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 */
 29extern u64 running_clock(void);
 30extern u64 sched_clock_cpu(int cpu);
 31
 32
 33extern void sched_clock_init(void);
 34
 35#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
 36static inline void sched_clock_tick(void)
 37{
 38}
 39
 40static inline void clear_sched_clock_stable(void)
 41{
 42}
 43
 44static inline void sched_clock_idle_sleep_event(void)
 45{
 46}
 47
 48static inline void sched_clock_idle_wakeup_event(void)
 49{
 50}
 51
 52static inline u64 cpu_clock(int cpu)
 53{
 54	return sched_clock();
 55}
 56
 57static __always_inline u64 local_clock_noinstr(void)
 58{
 59	return sched_clock_noinstr();
 60}
 61
 62static __always_inline u64 local_clock(void)
 63{
 64	return sched_clock();
 65}
 66#else
 67extern int sched_clock_stable(void);
 68extern 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 */
 74extern u64 __sched_clock_offset;
 75
 76extern void sched_clock_tick(void);
 77extern void sched_clock_tick_stable(void);
 78extern void sched_clock_idle_sleep_event(void);
 79extern 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 */
 91static inline u64 cpu_clock(int cpu)
 92{
 93	return sched_clock_cpu(cpu);
 94}
 95
 96extern u64 local_clock_noinstr(void);
 97extern 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 */
107extern void enable_sched_clock_irqtime(void);
108extern void disable_sched_clock_irqtime(void);
109#else
110static inline void enable_sched_clock_irqtime(void) {}
111static inline void disable_sched_clock_irqtime(void) {}
112#endif
113
114#endif /* _LINUX_SCHED_CLOCK_H */