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
  14 /*
  15  * When maximum proportion of some event type is specified, this is the
  16  * precision with which we allow limitting. Note that this creates an upper
  17  * bound on the number of events per period like
  18  *   ULLONG_MAX >> FPROP_FRAC_SHIFT.
  19  */
  20 #define FPROP_FRAC_SHIFT 10
  21 #define FPROP_FRAC_BASE (1UL << FPROP_FRAC_SHIFT)
  22
  23 /*
  24  * ---- Global proportion definitions ----
  25  */
  26 struct fprop_global {
  27         /* Number of events in the current period */
  28         struct percpu_counter events;
  29         /* Current period */
  30         unsigned int period;
  31         /* Synchronization with period transitions */
  32         seqcount_t sequence;
  33 };
  34
  35 int fprop_global_init(struct fprop_global *p);
  36 void fprop_global_destroy(struct fprop_global *p);
  37 bool fprop_new_period(struct fprop_global *p, int periods);
  38
  39 /*
  40  *  ---- SINGLE ----
  41  */
  42 struct fprop_local_single {
  43         /* the local events counter */
  44         unsigned long events;
  45         /* Period in which we last updated events */
  46         unsigned int period;
  47         raw_spinlock_t lock;    /* Protect period and numerator */
  48 };
  49
  50 #define INIT_FPROP_LOCAL_SINGLE(name)                   \
  51 {       .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock),    \
  52 }
  53
  54 int fprop_local_init_single(struct fprop_local_single *pl);
  55 void fprop_local_destroy_single(struct fprop_local_single *pl);
  56 void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
  57 void fprop_fraction_single(struct fprop_global *p,
  58         struct fprop_local_single *pl, unsigned long *numerator,
  59         unsigned long *denominator);
  60
  61 static inline
  62 void fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
  63 {
  64         unsigned long flags;
  65
  66         local_irq_save(flags);
  67         __fprop_inc_single(p, pl);
  68         local_irq_restore(flags);
  69 }
  70
  71 /*
  72  * ---- PERCPU ----
  73  */
  74 struct fprop_local_percpu {
  75         /* the local events counter */
  76         struct percpu_counter events;
  77         /* Period in which we last updated events */
  78         unsigned int period;
  79         raw_spinlock_t lock;    /* Protect period and numerator */
  80 };
  81
  82 int fprop_local_init_percpu(struct fprop_local_percpu *pl);
  83 void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
  84 void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
  85 void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
  86                             int max_frac);
  87 void fprop_fraction_percpu(struct fprop_global *p,
  88         struct fprop_local_percpu *pl, unsigned long *numerator,
  89         unsigned long *denominator);
  90
  91 static inline
  92 void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
  93 {
  94         unsigned long flags;
  95
  96         local_irq_save(flags);
  97         __fprop_inc_percpu(p, pl);
  98         local_irq_restore(flags);
  99 }
 100
 101 #endif