xref: /openbmc/linux/include/linux/sched/clock.h (revision fb7d4948) 
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
sched_clock_noinstr(void)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
sched_clock_tick(void)36 static inline void sched_clock_tick(void)
37 {
38 }
39 
clear_sched_clock_stable(void)40 static inline void clear_sched_clock_stable(void)
41 {
42 }
43 
sched_clock_idle_sleep_event(void)44 static inline void sched_clock_idle_sleep_event(void)
45 {
46 }
47 
sched_clock_idle_wakeup_event(void)48 static inline void sched_clock_idle_wakeup_event(void)
49 {
50 }
51 
cpu_clock(int cpu)52 static inline u64 cpu_clock(int cpu)
53 {
54 	return sched_clock();
55 }
56 
local_clock_noinstr(void)57 static __always_inline u64 local_clock_noinstr(void)
58 {
59 	return sched_clock_noinstr();
60 }
61 
local_clock(void)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  */
cpu_clock(int cpu)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
enable_sched_clock_irqtime(void)110 static inline void enable_sched_clock_irqtime(void) {}
disable_sched_clock_irqtime(void)111 static inline void disable_sched_clock_irqtime(void) {}
112 #endif
113 
114 #endif /* _LINUX_SCHED_CLOCK_H */
115