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