Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid
[linux-2.6] / include / linux / proportions.h
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
16 struct 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  */
37 struct prop_descriptor {
38         int index;
39         struct prop_global pg[2];
40         struct mutex mutex;             /* serialize the prop_global switch */
41 };
42
43 int prop_descriptor_init(struct prop_descriptor *pd, int shift);
44 void prop_change_shift(struct prop_descriptor *pd, int new_shift);
45
46 /*
47  * ----- PERCPU ------
48  */
49
50 struct 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
64 int prop_local_init_percpu(struct prop_local_percpu *pl);
65 void prop_local_destroy_percpu(struct prop_local_percpu *pl);
66 void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl);
67 void prop_fraction_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl,
68                 long *numerator, long *denominator);
69
70 static inline
71 void 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
84 struct 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
103 int prop_local_init_single(struct prop_local_single *pl);
104 void prop_local_destroy_single(struct prop_local_single *pl);
105 void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl);
106 void prop_fraction_single(struct prop_descriptor *pd, struct prop_local_single *pl,
107                 long *numerator, long *denominator);
108
109 static inline
110 void 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 */