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