diff options
Diffstat (limited to 'include/linux/sched_clock.h')
| -rw-r--r-- | include/linux/sched_clock.h | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h new file mode 100644 index 000000000..cb41c5edb --- /dev/null +++ b/include/linux/sched_clock.h @@ -0,0 +1,52 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * sched_clock.h: support for extending counters to full 64-bit ns counter + */ +#ifndef LINUX_SCHED_CLOCK +#define LINUX_SCHED_CLOCK + +#include <linux/types.h> + +#ifdef CONFIG_GENERIC_SCHED_CLOCK +/** + * struct clock_read_data - data required to read from sched_clock() + * + * @epoch_ns: sched_clock() value at last update + * @epoch_cyc: Clock cycle value at last update. + * @sched_clock_mask: Bitmask for two's complement subtraction of non 64bit + * clocks. + * @read_sched_clock: Current clock source (or dummy source when suspended). + * @mult: Multiplier for scaled math conversion. + * @shift: Shift value for scaled math conversion. + * + * Care must be taken when updating this structure; it is read by + * some very hot code paths. It occupies <=40 bytes and, when combined + * with the seqcount used to synchronize access, comfortably fits into + * a 64 byte cache line. + */ +struct clock_read_data { + u64 epoch_ns; + u64 epoch_cyc; + u64 sched_clock_mask; + u64 (*read_sched_clock)(void); + u32 mult; + u32 shift; +}; + +extern struct clock_read_data *sched_clock_read_begin(unsigned int *seq); +extern int sched_clock_read_retry(unsigned int seq); + +extern void generic_sched_clock_init(void); + +extern void sched_clock_register(u64 (*read)(void), int bits, + unsigned long rate); +#else +static inline void generic_sched_clock_init(void) { } + +static inline void sched_clock_register(u64 (*read)(void), int bits, + unsigned long rate) +{ +} +#endif + +#endif |