include/linux/flex_proportions.h

   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