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  */
27 struct 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 
36 int fprop_global_init(struct fprop_global *p, gfp_t gfp);
37 void fprop_global_destroy(struct fprop_global *p);
38 bool fprop_new_period(struct fprop_global *p, int periods);
39 
40 /*
41  *  ---- SINGLE ----
42  */
43 struct 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 
55 int fprop_local_init_single(struct fprop_local_single *pl);
56 void fprop_local_destroy_single(struct fprop_local_single *pl);
57 void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
58 void fprop_fraction_single(struct fprop_global *p,
59 	struct fprop_local_single *pl, unsigned long *numerator,
60 	unsigned long *denominator);
61 
62 static inline
63 void 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  */
75 struct 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 
83 int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
84 void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
85 void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
86 void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
87 			    int max_frac);
88 void fprop_fraction_percpu(struct fprop_global *p,
89 	struct fprop_local_percpu *pl, unsigned long *numerator,
90 	unsigned long *denominator);
91 
92 static inline
93 void 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