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