include/linux/flex_proportions.h

   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  */
  28 struct 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
  37 int fprop_global_init(struct fprop_global *p, gfp_t gfp);
  38 void fprop_global_destroy(struct fprop_global *p);
  39 bool fprop_new_period(struct fprop_global *p, int periods);
  40
  41 /*
  42  *  ---- SINGLE ----
  43  */
  44 struct fprop_local_single {
  45         /* the local events counter */
  46         unsigned long events;
  47         /* Period in which we last updated events */
  48         unsigned int period;
  49         raw_spinlock_t lock;    /* Protect period and numerator */
  50 };
  51
  52 #define INIT_FPROP_LOCAL_SINGLE(name)                   \
  53 {       .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock),    \
  54 }
  55
  56 int fprop_local_init_single(struct fprop_local_single *pl);
  57 void fprop_local_destroy_single(struct fprop_local_single *pl);
  58 void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
  59 void fprop_fraction_single(struct fprop_global *p,
  60         struct fprop_local_single *pl, unsigned long *numerator,
  61         unsigned long *denominator);
  62
  63 static inline
  64 void fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
  65 {
  66         unsigned long flags;
  67
  68         local_irq_save(flags);
  69         __fprop_inc_single(p, pl);
  70         local_irq_restore(flags);
  71 }
  72
  73 /*
  74  * ---- PERCPU ----
  75  */
  76 struct fprop_local_percpu {
  77         /* the local events counter */
  78         struct percpu_counter events;
  79         /* Period in which we last updated events */
  80         unsigned int period;
  81         raw_spinlock_t lock;    /* Protect period and numerator */
  82 };
  83
  84 int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
  85 void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
  86 void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
  87 void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
  88                             int max_frac);
  89 void fprop_fraction_percpu(struct fprop_global *p,
  90         struct fprop_local_percpu *pl, unsigned long *numerator,
  91         unsigned long *denominator);
  92
  93 static inline
  94 void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
  95 {
  96         unsigned long flags;
  97
  98         local_irq_save(flags);
  99         __fprop_inc_percpu(p, pl);
 100         local_irq_restore(flags);
 101 }
 102
 103 #endif