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1/*
2 * FLoating proportions
3 *
4 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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>
15
16struct prop_global {
17 /*
18 * The period over which we differentiate
19 *
20 * period = 2^shift
21 */
22 int shift;
23 /*
24 * The total event counter aka 'time'.
25 *
26 * Treated as an unsigned long; the lower 'shift - 1' bits are the
27 * counter bits, the remaining upper bits the period counter.
28 */
29 struct percpu_counter events;
30};
31
32/*
33 * global proportion descriptor
34 *
35 * this is needed to consitently flip prop_global structures.
36 */
37struct prop_descriptor {
38 int index;
39 struct prop_global pg[2];
40 struct mutex mutex; /* serialize the prop_global switch */
41};
42
43int prop_descriptor_init(struct prop_descriptor *pd, int shift);
44void prop_change_shift(struct prop_descriptor *pd, int new_shift);
45
46/*
47 * ----- PERCPU ------
48 */
49
50struct prop_local_percpu {
51 /*
52 * the local events counter
53 */
54 struct percpu_counter events;
55
56 /*
57 * snapshot of the last seen global state
58 */
59 int shift;
60 unsigned long period;
61 spinlock_t lock; /* protect the snapshot state */
62};
63
64int prop_local_init_percpu(struct prop_local_percpu *pl);
65void prop_local_destroy_percpu(struct prop_local_percpu *pl);
66void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl);
67void prop_fraction_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl,
68 long *numerator, long *denominator);
69
70static inline
71void prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl)
72{
73 unsigned long flags;
74
75 local_irq_save(flags);
76 __prop_inc_percpu(pd, pl);
77 local_irq_restore(flags);
78}
79
80/*
81 * ----- SINGLE ------
82 */
83
84struct prop_local_single {
85 /*
86 * the local events counter
87 */
88 unsigned long events;
89
90 /*
91 * snapshot of the last seen global state
92 * and a lock protecting this state
93 */
94 int shift;
95 unsigned long period;
96 spinlock_t lock; /* protect the snapshot state */
97};
98
99#define INIT_PROP_LOCAL_SINGLE(name) \
100{ .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
101}
102
103int prop_local_init_single(struct prop_local_single *pl);
104void prop_local_destroy_single(struct prop_local_single *pl);
105void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl);
106void prop_fraction_single(struct prop_descriptor *pd, struct prop_local_single *pl,
107 long *numerator, long *denominator);
108
109static inline
110void prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl)
111{
112 unsigned long flags;
113
114 local_irq_save(flags);
115 __prop_inc_single(pd, pl);
116 local_irq_restore(flags);
117}
118
119#endif /* _LINUX_PROPORTIONS_H */