1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Floating proportions with flexible aging period
4 *
5 * Copyright (C) 2011, SUSE, Jan Kara <jack@suse.cz>
6 */
7
8#ifndef _LINUX_FLEX_PROPORTIONS_H
9#define _LINUX_FLEX_PROPORTIONS_H
10
11#include <linux/percpu_counter.h>
12#include <linux/spinlock.h>
13#include <linux/seqlock.h>
14#include <linux/gfp.h>
15
16/*
17 * When maximum proportion of some event type is specified, this is the
18 * precision with which we allow limitting. Note that this creates an upper
19 * bound on the number of events per period like
20 * ULLONG_MAX >> FPROP_FRAC_SHIFT.
21 */
22#define FPROP_FRAC_SHIFT 10
23#define FPROP_FRAC_BASE (1UL << FPROP_FRAC_SHIFT)
24
25/*
26 * ---- Global proportion definitions ----
27 */
28struct fprop_global {
29 /* Number of events in the current period */
30 struct percpu_counter events;
31 /* Current period */
32 unsigned int period;
33 /* Synchronization with period transitions */
34 seqcount_t sequence;
35};
36
37int fprop_global_init(struct fprop_global *p, gfp_t gfp);
38void fprop_global_destroy(struct fprop_global *p);
39bool fprop_new_period(struct fprop_global *p, int periods);
40
41/*
42 * ---- PERCPU ----
43 */
44struct fprop_local_percpu {
45 /* the local events counter */
46 struct percpu_counter events;
47 /* Period in which we last updated events */
48 unsigned int period;
49 raw_spinlock_t lock; /* Protect period and numerator */
50};
51
52int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
53void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
54void __fprop_add_percpu(struct fprop_global *p, struct fprop_local_percpu *pl,
55 long nr);
56void __fprop_add_percpu_max(struct fprop_global *p,
57 struct fprop_local_percpu *pl, int max_frac, long nr);
58void fprop_fraction_percpu(struct fprop_global *p,
59 struct fprop_local_percpu *pl, unsigned long *numerator,
60 unsigned long *denominator);
61
62static inline
63void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
64{
65 unsigned long flags;
66
67 local_irq_save(flags);
68 __fprop_add_percpu(p, pl, nr: 1);
69 local_irq_restore(flags);
70}
71
72#endif
73