forked from mirrors/linux
8c5db92a70
Conflicts: include/linux/compiler-clang.h include/linux/compiler-gcc.h include/linux/compiler-intel.h include/uapi/linux/stddef.h Signed-off-by: Ingo Molnar <mingo@kernel.org>
71 lines
2.4 KiB
C
71 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_AVERAGE_H
|
|
#define _LINUX_AVERAGE_H
|
|
|
|
#include <linux/bug.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/log2.h>
|
|
|
|
/*
|
|
* 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) \
|
|
{ \
|
|
BUILD_BUG_ON(!__builtin_constant_p(_precision)); \
|
|
BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \
|
|
/* \
|
|
* Even if you want to feed it just 0/1 you should have \
|
|
* some bits for the non-fractional part... \
|
|
*/ \
|
|
BUILD_BUG_ON((_precision) > 30); \
|
|
BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \
|
|
e->internal = 0; \
|
|
} \
|
|
static inline unsigned long \
|
|
ewma_##name##_read(struct ewma_##name *e) \
|
|
{ \
|
|
BUILD_BUG_ON(!__builtin_constant_p(_precision)); \
|
|
BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \
|
|
BUILD_BUG_ON((_precision) > 30); \
|
|
BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \
|
|
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; \
|
|
\
|
|
BUILD_BUG_ON(!__builtin_constant_p(_precision)); \
|
|
BUILD_BUG_ON(!__builtin_constant_p(_weight_rcp)); \
|
|
BUILD_BUG_ON((_precision) > 30); \
|
|
BUILD_BUG_ON_NOT_POWER_OF_2(_weight_rcp); \
|
|
\
|
|
WRITE_ONCE(e->internal, internal ? \
|
|
(((internal << weight_rcp) - internal) + \
|
|
(val << precision)) >> weight_rcp : \
|
|
(val << precision)); \
|
|
}
|
|
|
|
#endif /* _LINUX_AVERAGE_H */
|