include/qemu/throttle.h

   1 /*
   2  * QEMU throttling infrastructure
   3  *
   4  * Copyright (C) Nodalink, EURL. 2013-2014
   5  * Copyright (C) Igalia, S.L. 2015
   6  *
   7  * Authors:
   8  *   Benoît Canet <benoit.canet@nodalink.com>
   9  *   Alberto Garcia <berto@igalia.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 or
  14  * (at your option) version 3 of the License.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  23  */
  24
  25 #ifndef THROTTLE_H
  26 #define THROTTLE_H
  27
  28 #include <stdint.h>
  29 #include "qemu-common.h"
  30 #include "qemu/timer.h"
  31
  32 typedef enum {
  33     THROTTLE_BPS_TOTAL,
  34     THROTTLE_BPS_READ,
  35     THROTTLE_BPS_WRITE,
  36     THROTTLE_OPS_TOTAL,
  37     THROTTLE_OPS_READ,
  38     THROTTLE_OPS_WRITE,
  39     BUCKETS_COUNT,
  40 } BucketType;
  41
  42 /*
  43  * The max parameter of the leaky bucket throttling algorithm can be used to
  44  * allow the guest to do bursts.
  45  * The max value is a pool of I/O that the guest can use without being throttled
  46  * at all. Throttling is triggered once this pool is empty.
  47  */
  48
  49 typedef struct LeakyBucket {
  50     double  avg;              /* average goal in units per second */
  51     double  max;              /* leaky bucket max burst in units */
  52     double  level;            /* bucket level in units */
  53 } LeakyBucket;
  54
  55 /* The following structure is used to configure a ThrottleState
  56  * It contains a bit of state: the bucket field of the LeakyBucket structure.
  57  * However it allows to keep the code clean and the bucket field is reset to
  58  * zero at the right time.
  59  */
  60 typedef struct ThrottleConfig {
  61     LeakyBucket buckets[BUCKETS_COUNT]; /* leaky buckets */
  62     uint64_t op_size;         /* size of an operation in bytes */
  63 } ThrottleConfig;
  64
  65 typedef struct ThrottleState {
  66     ThrottleConfig cfg;       /* configuration */
  67     int64_t previous_leak;    /* timestamp of the last leak done */
  68 } ThrottleState;
  69
  70 typedef struct ThrottleTimers {
  71     QEMUTimer *timers[2];     /* timers used to do the throttling */
  72     QEMUClockType clock_type; /* the clock used */
  73
  74     /* Callbacks */
  75     QEMUTimerCB *read_timer_cb;
  76     QEMUTimerCB *write_timer_cb;
  77     void *timer_opaque;
  78 } ThrottleTimers;
  79
  80 /* operations on single leaky buckets */
  81 void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);
  82
  83 int64_t throttle_compute_wait(LeakyBucket *bkt);
  84
  85 /* expose timer computation function for unit tests */
  86 bool throttle_compute_timer(ThrottleState *ts,
  87                             bool is_write,
  88                             int64_t now,
  89                             int64_t *next_timestamp);
  90
  91 /* init/destroy cycle */
  92 void throttle_init(ThrottleState *ts);
  93
  94 void throttle_timers_init(ThrottleTimers *tt,
  95                           AioContext *aio_context,
  96                           QEMUClockType clock_type,
  97                           QEMUTimerCB *read_timer_cb,
  98                           QEMUTimerCB *write_timer_cb,
  99                           void *timer_opaque);
 100
 101 void throttle_timers_destroy(ThrottleTimers *tt);
 102
 103 void throttle_timers_detach_aio_context(ThrottleTimers *tt);
 104
 105 void throttle_timers_attach_aio_context(ThrottleTimers *tt,
 106                                         AioContext *new_context);
 107
 108 bool throttle_timers_are_initialized(ThrottleTimers *tt);
 109
 110 /* configuration */
 111 bool throttle_enabled(ThrottleConfig *cfg);
 112
 113 bool throttle_conflicting(ThrottleConfig *cfg);
 114
 115 bool throttle_is_valid(ThrottleConfig *cfg);
 116
 117 bool throttle_max_is_missing_limit(ThrottleConfig *cfg);
 118
 119 void throttle_config(ThrottleState *ts,
 120                      ThrottleTimers *tt,
 121                      ThrottleConfig *cfg);
 122
 123 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
 124
 125 /* usage */
 126 bool throttle_schedule_timer(ThrottleState *ts,
 127                              ThrottleTimers *tt,
 128                              bool is_write);
 129
 130 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
 131
 132 #endif