[linux-2.6-block.git] / include / linux / average.h

#ifndef _LINUX_AVERAGE_H
#define _LINUX_AVERAGE_H

/* Exponentially weighted moving average (EWMA) */

#define DECLARE_EWMA(name, _factor, _weight)				\
	struct ewma_##name {						\
		unsigned long internal;					\
	};								\
	static inline void ewma_##name##_init(struct ewma_##name *e)	\
	{								\
		BUILD_BUG_ON(!__builtin_constant_p(_factor));		\
		BUILD_BUG_ON(!__builtin_constant_p(_weight));		\
		BUILD_BUG_ON_NOT_POWER_OF_2(_factor);			\
		BUILD_BUG_ON_NOT_POWER_OF_2(_weight);			\
		e->internal = 0;					\
	}								\
	static inline unsigned long					\
	ewma_##name##_read(struct ewma_##name *e)			\
	{								\
		BUILD_BUG_ON(!__builtin_constant_p(_factor));		\
		BUILD_BUG_ON(!__builtin_constant_p(_weight));		\
		BUILD_BUG_ON_NOT_POWER_OF_2(_factor);			\
		BUILD_BUG_ON_NOT_POWER_OF_2(_weight);			\
		return e->internal >> ilog2(_factor);			\
	}								\
	static inline void ewma_##name##_add(struct ewma_##name *e,	\
					     unsigned long val)		\
	{								\
		unsigned long internal = ACCESS_ONCE(e->internal);	\
		unsigned long weight = ilog2(_weight);			\
		unsigned long factor = ilog2(_factor);			\
									\
		BUILD_BUG_ON(!__builtin_constant_p(_factor));		\
		BUILD_BUG_ON(!__builtin_constant_p(_weight));		\
		BUILD_BUG_ON_NOT_POWER_OF_2(_factor);			\
		BUILD_BUG_ON_NOT_POWER_OF_2(_weight);			\
									\
		ACCESS_ONCE(e->internal) = internal ?			\
			(((internal << weight) - internal) +		\
				(val << factor)) >> weight :		\
			(val << factor);				\
	}

#endif /* _LINUX_AVERAGE_H */
Commit	Line	Data
c5485a7e BR	1	#ifndef _LINUX_AVERAGE_H
	2	#define _LINUX_AVERAGE_H
	3
c5485a7e BR	4	/* Exponentially weighted moving average (EWMA) */
c5485a7e BR	5
2377799c JB	6	#define DECLARE_EWMA(name, _factor, _weight) \
	7	struct ewma_##name { \
	8	unsigned long internal; \
	9	}; \
	10	static inline void ewma_##name##_init(struct ewma_##name *e) \
	11	{ \
	12	BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
	13	BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
	14	BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
	15	BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
	16	e->internal = 0; \
	17	} \
	18	static inline unsigned long \
	19	ewma_##name##_read(struct ewma_##name *e) \
	20	{ \
	21	BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
	22	BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
	23	BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
	24	BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
	25	return e->internal >> ilog2(_factor); \
	26	} \
	27	static inline void ewma_##name##_add(struct ewma_##name *e, \
	28	unsigned long val) \
	29	{ \
	30	unsigned long internal = ACCESS_ONCE(e->internal); \
	31	unsigned long weight = ilog2(_weight); \
	32	unsigned long factor = ilog2(_factor); \
	33	\
	34	BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
	35	BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
	36	BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
	37	BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
	38	\
	39	ACCESS_ONCE(e->internal) = internal ? \
	40	(((internal << weight) - internal) + \
	41	(val << factor)) >> weight : \
	42	(val << factor); \
	43	}
	44
c5485a7e	45	#endif /* _LINUX_AVERAGE_H */