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/* 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
#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: Multipler 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
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