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

/*
 * FLoating proportions
 *
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
 *
 * This file contains the public data structure and API definitions.
 */

#ifndef _LINUX_PROPORTIONS_H
#define _LINUX_PROPORTIONS_H

#include <linux/percpu_counter.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/gfp.h>

struct prop_global {
	/*
	 * The period over which we differentiate
	 *
	 *   period = 2^shift
	 */
	int shift;
	/*
	 * The total event counter aka 'time'.
	 *
	 * Treated as an unsigned long; the lower 'shift - 1' bits are the
	 * counter bits, the remaining upper bits the period counter.
	 */
	struct percpu_counter events;
};

/*
 * global proportion descriptor
 *
 * this is needed to consistently flip prop_global structures.
 */
struct prop_descriptor {
	int index;
	struct prop_global pg[2];
	struct mutex mutex;		/* serialize the prop_global switch */
};

int prop_descriptor_init(struct prop_descriptor *pd, int shift, gfp_t gfp);
void prop_change_shift(struct prop_descriptor *pd, int new_shift);

/*
 * ----- PERCPU ------
 */

struct prop_local_percpu {
	/*
	 * the local events counter
	 */
	struct percpu_counter events;

	/*
	 * snapshot of the last seen global state
	 */
	int shift;
	unsigned long period;
	raw_spinlock_t lock;		/* protect the snapshot state */
};

int prop_local_init_percpu(struct prop_local_percpu *pl, gfp_t gfp);
void prop_local_destroy_percpu(struct prop_local_percpu *pl);
void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl);
void prop_fraction_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl,
		long *numerator, long *denominator);

static inline
void prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl)
{
	unsigned long flags;

	local_irq_save(flags);
	__prop_inc_percpu(pd, pl);
	local_irq_restore(flags);
}

/*
 * Limit the time part in order to ensure there are some bits left for the
 * cycle counter and fraction multiply.
 */
#if BITS_PER_LONG == 32
#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4)
#else
#define PROP_MAX_SHIFT (BITS_PER_LONG/2)
#endif

#define PROP_FRAC_SHIFT		(BITS_PER_LONG - PROP_MAX_SHIFT - 1)
#define PROP_FRAC_BASE		(1UL << PROP_FRAC_SHIFT)

void __prop_inc_percpu_max(struct prop_descriptor *pd,
			   struct prop_local_percpu *pl, long frac);


/*
 * ----- SINGLE ------
 */

struct prop_local_single {
	/*
	 * the local events counter
	 */
	unsigned long events;

	/*
	 * snapshot of the last seen global state
	 * and a lock protecting this state
	 */
	unsigned long period;
	int shift;
	raw_spinlock_t lock;		/* protect the snapshot state */
};

#define INIT_PROP_LOCAL_SINGLE(name)			\
{	.lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock),	\
}

int prop_local_init_single(struct prop_local_single *pl);
void prop_local_destroy_single(struct prop_local_single *pl);
void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl);
void prop_fraction_single(struct prop_descriptor *pd, struct prop_local_single *pl,
		long *numerator, long *denominator);

static inline
void prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl)
{
	unsigned long flags;

	local_irq_save(flags);
	__prop_inc_single(pd, pl);
	local_irq_restore(flags);
}

#endif /* _LINUX_PROPORTIONS_H */
Commit	Line	Data
145ca25e PZ	1	/*
	2	* FLoating proportions
	3	*
90eec103	4	* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
145ca25e PZ	5	*
	6	* This file contains the public data structure and API definitions.
	7	*/
	8
	9	#ifndef _LINUX_PROPORTIONS_H
	10	#define _LINUX_PROPORTIONS_H
	11
	12	#include <linux/percpu_counter.h>
	13	#include <linux/spinlock.h>
	14	#include <linux/mutex.h>
20ae0079	15	#include <linux/gfp.h>
145ca25e PZ	16
	17	struct prop_global {
	18	/*
	19	* The period over which we differentiate
	20	*
	21	* period = 2^shift
	22	*/
	23	int shift;
	24	/*
	25	* The total event counter aka 'time'.
	26	*
	27	* Treated as an unsigned long; the lower 'shift - 1' bits are the
	28	* counter bits, the remaining upper bits the period counter.
	29	*/
	30	struct percpu_counter events;
	31	};
	32
	33	/*
	34	* global proportion descriptor
	35	*
377a51a6	36	* this is needed to consistently flip prop_global structures.
145ca25e PZ	37	*/
	38	struct prop_descriptor {
	39	int index;
	40	struct prop_global pg[2];
	41	struct mutex mutex; /* serialize the prop_global switch */
	42	};
	43
20ae0079	44	int prop_descriptor_init(struct prop_descriptor *pd, int shift, gfp_t gfp);
145ca25e PZ	45	void prop_change_shift(struct prop_descriptor *pd, int new_shift);
	46
	47	/*
	48	* ----- PERCPU ------
	49	*/
	50
	51	struct prop_local_percpu {
	52	/*
	53	* the local events counter
	54	*/
	55	struct percpu_counter events;
	56
	57	/*
	58	* snapshot of the last seen global state
	59	*/
	60	int shift;
	61	unsigned long period;
740969f9	62	raw_spinlock_t lock; /* protect the snapshot state */
145ca25e PZ	63	};
145ca25e PZ	64
20ae0079	65	int prop_local_init_percpu(struct prop_local_percpu *pl, gfp_t gfp);
145ca25e PZ	66	void prop_local_destroy_percpu(struct prop_local_percpu *pl);
	67	void __prop_inc_percpu(struct prop_descriptor pd, struct prop_local_percpu pl);
	68	void prop_fraction_percpu(struct prop_descriptor pd, struct prop_local_percpu pl,
	69	long numerator, long denominator);
	70
	71	static inline
	72	void prop_inc_percpu(struct prop_descriptor pd, struct prop_local_percpu pl)
	73	{
	74	unsigned long flags;
	75
	76	local_irq_save(flags);
	77	__prop_inc_percpu(pd, pl);
	78	local_irq_restore(flags);
	79	}
	80
a42dde04 PZ	81	/*
	82	* Limit the time part in order to ensure there are some bits left for the
	83	* cycle counter and fraction multiply.
	84	*/
3310225d	85	#if BITS_PER_LONG == 32
a42dde04	86	#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4)
3310225d WF	87	#else
	88	#define PROP_MAX_SHIFT (BITS_PER_LONG/2)
	89	#endif
a42dde04 PZ	90
	91	#define PROP_FRAC_SHIFT (BITS_PER_LONG - PROP_MAX_SHIFT - 1)
	92	#define PROP_FRAC_BASE (1UL << PROP_FRAC_SHIFT)
	93
	94	void __prop_inc_percpu_max(struct prop_descriptor *pd,
	95	struct prop_local_percpu *pl, long frac);
	96
	97
145ca25e PZ	98	/*
	99	* ----- SINGLE ------
	100	*/
	101
	102	struct prop_local_single {
	103	/*
	104	* the local events counter
	105	*/
	106	unsigned long events;
	107
	108	/*
	109	* snapshot of the last seen global state
	110	* and a lock protecting this state
	111	*/
145ca25e	112	unsigned long period;
3fb669dd	113	int shift;
740969f9	114	raw_spinlock_t lock; /* protect the snapshot state */
145ca25e PZ	115	};
	116
	117	#define INIT_PROP_LOCAL_SINGLE(name) \
740969f9	118	{ .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
145ca25e PZ	119	}
	120
	121	int prop_local_init_single(struct prop_local_single *pl);
	122	void prop_local_destroy_single(struct prop_local_single *pl);
	123	void __prop_inc_single(struct prop_descriptor pd, struct prop_local_single pl);
	124	void prop_fraction_single(struct prop_descriptor pd, struct prop_local_single pl,
	125	long numerator, long denominator);
	126
	127	static inline
	128	void prop_inc_single(struct prop_descriptor pd, struct prop_local_single pl)
	129	{
	130	unsigned long flags;
	131
	132	local_irq_save(flags);
	133	__prop_inc_single(pd, pl);
	134	local_irq_restore(flags);
	135	}
	136
	137	#endif /* _LINUX_PROPORTIONS_H */