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 #define THROTTLE_VALUE_MAX 1000000000000000LL
  33
  34 typedef enum {
  35     THROTTLE_BPS_TOTAL,
  36     THROTTLE_BPS_READ,
  37     THROTTLE_BPS_WRITE,
  38     THROTTLE_OPS_TOTAL,
  39     THROTTLE_OPS_READ,
  40     THROTTLE_OPS_WRITE,
  41     BUCKETS_COUNT,
  42 } BucketType;
  43
  44 /*
  45  * The max parameter of the leaky bucket throttling algorithm can be used to
  46  * allow the guest to do bursts.
  47  * The max value is a pool of I/O that the guest can use without being throttled
  48  * at all. Throttling is triggered once this pool is empty.
  49  */
  50
  51 typedef struct LeakyBucket {
  52     double  avg;              /* average goal in units per second */
  53     double  max;              /* leaky bucket max burst in units */
  54     double  level;            /* bucket level in units */
  55 } LeakyBucket;
  56
  57 /* The following structure is used to configure a ThrottleState
  58  * It contains a bit of state: the bucket field of the LeakyBucket structure.
  59  * However it allows to keep the code clean and the bucket field is reset to
  60  * zero at the right time.
  61  */
  62 typedef struct ThrottleConfig {
  63     LeakyBucket buckets[BUCKETS_COUNT]; /* leaky buckets */
  64     uint64_t op_size;         /* size of an operation in bytes */
  65 } ThrottleConfig;
  66
  67 typedef struct ThrottleState {
  68     ThrottleConfig cfg;       /* configuration */
  69     int64_t previous_leak;    /* timestamp of the last leak done */
  70 } ThrottleState;
  71
  72 typedef struct ThrottleTimers {
  73     QEMUTimer *timers[2];     /* timers used to do the throttling */
  74     QEMUClockType clock_type; /* the clock used */
  75
  76     /* Callbacks */
  77     QEMUTimerCB *read_timer_cb;
  78     QEMUTimerCB *write_timer_cb;
  79     void *timer_opaque;
  80 } ThrottleTimers;
  81
  82 /* operations on single leaky buckets */
  83 void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);
  84
  85 int64_t throttle_compute_wait(LeakyBucket *bkt);
  86
  87 /* expose timer computation function for unit tests */
  88 bool throttle_compute_timer(ThrottleState *ts,
  89                             bool is_write,
  90                             int64_t now,
  91                             int64_t *next_timestamp);
  92
  93 /* init/destroy cycle */
  94 void throttle_init(ThrottleState *ts);
  95
  96 void throttle_timers_init(ThrottleTimers *tt,
  97                           AioContext *aio_context,
  98                           QEMUClockType clock_type,
  99                           QEMUTimerCB *read_timer_cb,
 100                           QEMUTimerCB *write_timer_cb,
 101                           void *timer_opaque);
 102
 103 void throttle_timers_destroy(ThrottleTimers *tt);
 104
 105 void throttle_timers_detach_aio_context(ThrottleTimers *tt);
 106
 107 void throttle_timers_attach_aio_context(ThrottleTimers *tt,
 108                                         AioContext *new_context);
 109
 110 bool throttle_timers_are_initialized(ThrottleTimers *tt);
 111
 112 /* configuration */
 113 bool throttle_enabled(ThrottleConfig *cfg);
 114
 115 bool throttle_conflicting(ThrottleConfig *cfg);
 116
 117 bool throttle_is_valid(ThrottleConfig *cfg);
 118
 119 bool throttle_max_is_missing_limit(ThrottleConfig *cfg);
 120
 121 void throttle_config(ThrottleState *ts,
 122                      ThrottleTimers *tt,
 123                      ThrottleConfig *cfg);
 124
 125 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
 126
 127 /* usage */
 128 bool throttle_schedule_timer(ThrottleState *ts,
 129                              ThrottleTimers *tt,
 130                              bool is_write);
 131
 132 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
 133
 134 #endif