1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * sched_clock.h: support for extending counters to full 64-bit ns counter 4 */ 5 #ifndef LINUX_SCHED_CLOCK 6 #define LINUX_SCHED_CLOCK 7 8 #include <linux/types.h> 9 10 #ifdef CONFIG_GENERIC_SCHED_CLOCK 11 /** 12 * struct clock_read_data - data required to read from sched_clock() 13 * 14 * @epoch_ns: sched_clock() value at last update 15 * @epoch_cyc: Clock cycle value at last update. 16 * @sched_clock_mask: Bitmask for two's complement subtraction of non 64bit 17 * clocks. 18 * @read_sched_clock: Current clock source (or dummy source when suspended). 19 * @mult: Multiplier for scaled math conversion. 20 * @shift: Shift value for scaled math conversion. 21 * 22 * Care must be taken when updating this structure; it is read by 23 * some very hot code paths. It occupies <=40 bytes and, when combined 24 * with the seqcount used to synchronize access, comfortably fits into 25 * a 64 byte cache line. 26 */ 27 struct clock_read_data { 28 u64 epoch_ns; 29 u64 epoch_cyc; 30 u64 sched_clock_mask; 31 u64 (*read_sched_clock)(void); 32 u32 mult; 33 u32 shift; 34 }; 35 36 extern struct clock_read_data *sched_clock_read_begin(unsigned int *seq); 37 extern int sched_clock_read_retry(unsigned int seq); 38 39 extern void generic_sched_clock_init(void); 40 41 extern void sched_clock_register(u64 (*read)(void), int bits, 42 unsigned long rate); 43 #else generic_sched_clock_init(void)44static inline void generic_sched_clock_init(void) { } 45 sched_clock_register(u64 (* read)(void),int bits,unsigned long rate)46static inline void sched_clock_register(u64 (*read)(void), int bits, 47 unsigned long rate) 48 { 49 } 50 #endif 51 52 #endif 53