/*
* Floating proportions with flexible aging period
*
* Copyright (C) 2011, SUSE, Jan Kara <[email protected]>
*/

#ifndef _LINUX_FLEX_PROPORTIONS_H
#define _LINUX_FLEX_PROPORTIONS_H

#include <linux/percpu_counter.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>

/*
* When maximum proportion of some event type is specified, this is the
* precision with which we allow limitting. Note that this creates an upper
* bound on the number of events per period like
* ULLONG_MAX >> FPROP_FRAC_SHIFT.
*/
#define FPROP_FRAC_SHIFT 10
#define FPROP_FRAC_BASE (1UL << FPROP_FRAC_SHIFT)

/*
* ---- Global proportion definitions ----
*/
struct fprop_global {
/* Number of events in the current period */
struct percpu_counter events;
/* Current period */
unsigned int period;
/* Synchronization with period transitions */
seqcount_t sequence;
};

int fprop_global_init(struct fprop_global *p);
void fprop_global_destroy(struct fprop_global *p);
bool fprop_new_period(struct fprop_global *p, int periods);

/*
* ---- SINGLE ----
*/
struct fprop_local_single {
/* the local events counter */
unsigned long events;
/* Period in which we last updated events */
unsigned int period;
raw_spinlock_t lock; /* Protect period and numerator */
};

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

int fprop_local_init_single(struct fprop_local_single *pl);
void fprop_local_destroy_single(struct fprop_local_single *pl);
void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
void fprop_fraction_single(struct fprop_global *p,
struct fprop_local_single *pl, unsigned long *numerator,
unsigned long *denominator);

static inline
void fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
{
unsigned long flags;

local_irq_save(flags);
__fprop_inc_single(p, pl);
local_irq_restore(flags);
}

/*
* ---- PERCPU ----
*/
struct fprop_local_percpu {
/* the local events counter */
struct percpu_counter events;
/* Period in which we last updated events */
unsigned int period;
raw_spinlock_t lock; /* Protect period and numerator */
};

int fprop_local_init_percpu(struct fprop_local_percpu *pl);
void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
int max_frac);
void fprop_fraction_percpu(struct fprop_global *p,
struct fprop_local_percpu *pl, unsigned long *numerator,
unsigned long *denominator);

static inline
void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
{
unsigned long flags;

local_irq_save(flags);
__fprop_inc_percpu(p, pl);
local_irq_restore(flags);
}

#endif