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 */
115
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