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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 | |
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 | * Limit the time part in order to ensure there are some bits left for the |
82 | * cycle counter and fraction multiply. |
83 | */ |
84 | #define PROP_MAX_SHIFT (3*BITS_PER_LONG/4) |
85 | |
86 | #define PROP_FRAC_SHIFT (BITS_PER_LONG - PROP_MAX_SHIFT - 1) |
87 | #define PROP_FRAC_BASE (1UL << PROP_FRAC_SHIFT) |
88 | |
89 | void __prop_inc_percpu_max(struct prop_descriptor *pd, |
90 | struct prop_local_percpu *pl, long frac); |
91 | |
92 | |
93 | /* |
94 | * ----- SINGLE ------ |
95 | */ |
96 | |
97 | struct prop_local_single { |
98 | /* |
99 | * the local events counter |
100 | */ |
101 | unsigned long events; |
102 | |
103 | /* |
104 | * snapshot of the last seen global state |
105 | * and a lock protecting this state |
106 | */ |
107 | unsigned long period; |
108 | int shift; |
109 | spinlock_t lock; /* protect the snapshot state */ |
110 | }; |
111 | |
112 | #define INIT_PROP_LOCAL_SINGLE(name) \ |
113 | { .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ |
114 | } |
115 | |
116 | int prop_local_init_single(struct prop_local_single *pl); |
117 | void prop_local_destroy_single(struct prop_local_single *pl); |
118 | void __prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl); |
119 | void prop_fraction_single(struct prop_descriptor *pd, struct prop_local_single *pl, |
120 | long *numerator, long *denominator); |
121 | |
122 | static inline |
123 | void prop_inc_single(struct prop_descriptor *pd, struct prop_local_single *pl) |
124 | { |
125 | unsigned long flags; |
126 | |
127 | local_irq_save(flags); |
128 | __prop_inc_single(pd, pl); |
129 | local_irq_restore(flags); |
130 | } |
131 | |
132 | #endif /* _LINUX_PROPORTIONS_H */ |
133 |
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