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  * ---- PERCPU ----
  43  */
  44 struct 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
  52 int fprop_local_init_percpu(struct fprop_local_percpu *pl, gfp_t gfp);
  53 void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
  54 void __fprop_add_percpu(struct fprop_global *p, struct fprop_local_percpu *pl,
  55                 long nr);
  56 void __fprop_add_percpu_max(struct fprop_global *p,
  57                 struct fprop_local_percpu *pl, int max_frac, long nr);
  58 void fprop_fraction_percpu(struct fprop_global *p,
  59         struct fprop_local_percpu *pl, unsigned long *numerator,
  60         unsigned long *denominator);
  61
  62 static inline
  63 void 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, 1);
  69         local_irq_restore(flags);
  70 }
  71
  72 #endif