1/*
2 * Floating proportions with flexible aging period
3 *
4 *  Copyright (C) 2011, SUSE, Jan Kara <jack@suse.cz>
5 */
6
7#ifndef _LINUX_FLEX_PROPORTIONS_H
8#define _LINUX_FLEX_PROPORTIONS_H
9
10#include <linux/percpu_counter.h>
11#include <linux/spinlock.h>
12#include <linux/seqlock.h>
13#include <linux/gfp.h>
14
15/*
16 * When maximum proportion of some event type is specified, this is the
17 * precision with which we allow limitting. Note that this creates an upper
18 * bound on the number of events per period like
19 *   ULLONG_MAX >> FPROP_FRAC_SHIFT.
20 */
21#define FPROP_FRAC_SHIFT 10
22#define FPROP_FRAC_BASE (1UL << FPROP_FRAC_SHIFT)
23
24/*
25 * ---- Global proportion definitions ----
26 */
27struct fprop_global {
28	/* Number of events in the current period */
29	struct percpu_counter events;
30	/* Current period */
31	unsigned int period;
32	/* Synchronization with period transitions */
33	seqcount_t sequence;
34};
35
36int fprop_global_init(struct fprop_global *p, gfp_t gfp);
37void fprop_global_destroy(struct fprop_global *p);
38bool fprop_new_period(struct fprop_global *p, int periods);
39
40/*
41 *  ---- SINGLE ----
42 */
43struct fprop_local_single {
44	/* the local events counter */
45	unsigned long events;
46	/* Period in which we last updated events */
47	unsigned int period;
48	raw_spinlock_t lock;	/* Protect period and numerator */
49};
50
51#define INIT_FPROP_LOCAL_SINGLE(name)			\
52{	.lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock),	\
53}
54
55int fprop_local_init_single(struct fprop_local_single *pl);
56void fprop_local_destroy_single(struct fprop_local_single *pl);
57void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
58void fprop_fraction_single(struct fprop_global *p,
59	struct fprop_local_single *pl, unsigned long *numerator,
60	unsigned long *denominator);
61
62static inline
63void fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
64{
65	unsigned long flags;
66
67	local_irq_save(flags);
68	__fprop_inc_single(p, pl);
69	local_irq_restore(flags);
70}
71
72/*
73 * ---- PERCPU ----
74 */
75struct fprop_local_percpu {
76	/* the local events counter */
77	struct percpu_counter events;
78	/* Period in which we last updated events */
79	unsigned int period;
80	raw_spinlock_t lock;	/* Protect period and numerator */
81};
82
83int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
84void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
85void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
86void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
87			    int max_frac);
88void fprop_fraction_percpu(struct fprop_global *p,
89	struct fprop_local_percpu *pl, unsigned long *numerator,
90	unsigned long *denominator);
91
92static inline
93void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
94{
95	unsigned long flags;
96
97	local_irq_save(flags);
98	__fprop_inc_percpu(p, pl);
99	local_irq_restore(flags);
100}
101
102#endif
103