mirror of
https://gitee.com/Vancouver2017/luban-lite.git
synced 2025-12-21 19:48:55 +00:00
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
|
#ifndef _LINUX_AVERAGE_H
|
||
|
|
#define _LINUX_AVERAGE_H
|
||
|
|
|
||
|
|
/* Exponentially weighted moving average (EWMA) */
|
||
|
|
|
||
|
|
/* For more documentation see lib/average.c */
|
||
|
|
|
||
|
|
struct ewma {
|
||
|
|
unsigned long internal;
|
||
|
|
unsigned long factor;
|
||
|
|
unsigned long weight;
|
||
|
|
};
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Exponentially weighted moving average (EWMA)
|
||
|
|
*
|
||
|
|
* This implements a fixed-precision EWMA algorithm, with both the
|
||
|
|
* precision and fall-off coefficient determined at compile-time
|
||
|
|
* and built into the generated helper funtions.
|
||
|
|
*
|
||
|
|
* The first argument to the macro is the name that will be used
|
||
|
|
* for the struct and helper functions.
|
||
|
|
*
|
||
|
|
* The second argument, the precision, expresses how many bits are
|
||
|
|
* used for the fractional part of the fixed-precision values.
|
||
|
|
*
|
||
|
|
* The third argument, the weight reciprocal, determines how the
|
||
|
|
* new values will be weighed vs. the old state, new values will
|
||
|
|
* get weight 1/weight_rcp and old values 1-1/weight_rcp. Note
|
||
|
|
* that this parameter must be a power of two for efficiency.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#define DECLARE_EWMA(name, _precision, _weight_rcp) \
|
||
|
|
struct ewma_##name { \
|
||
|
|
unsigned long internal; \
|
||
|
|
}; \
|
||
|
|
static inline void ewma_##name##_init(struct ewma_##name *e) \
|
||
|
|
{ \
|
||
|
|
e->internal = 0; \
|
||
|
|
} \
|
||
|
|
static inline unsigned long \
|
||
|
|
ewma_##name##_read(struct ewma_##name *e) \
|
||
|
|
{ \
|
||
|
|
return e->internal >> (_precision); \
|
||
|
|
} \
|
||
|
|
static inline void ewma_##name##_add(struct ewma_##name *e, \
|
||
|
|
unsigned long val) \
|
||
|
|
{ \
|
||
|
|
unsigned long internal = READ_ONCE(e->internal); \
|
||
|
|
unsigned long weight_rcp = ilog2(_weight_rcp); \
|
||
|
|
unsigned long precision = _precision; \
|
||
|
|
WRITE_ONCE(e->internal, internal ? \
|
||
|
|
(((internal << weight_rcp) - internal) + \
|
||
|
|
(val << precision)) >> weight_rcp : \
|
||
|
|
(val << precision)); \
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
extern void ewma_init(struct ewma *avg, unsigned long factor,
|
||
|
|
unsigned long weight);
|
||
|
|
|
||
|
|
extern struct ewma *ewma_add(struct ewma *avg, unsigned long val);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* ewma_read() - Get average value
|
||
|
|
* @avg: Average structure
|
||
|
|
*
|
||
|
|
* Returns the average value held in @avg.
|
||
|
|
*/
|
||
|
|
static inline unsigned long ewma_read(const struct ewma *avg)
|
||
|
|
{
|
||
|
|
return avg->internal >> avg->factor;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* _LINUX_AVERAGE_H */
|