include/qemu/throttle.h

   1 /*
   2  * QEMU throttling infrastructure
   3  *
   4  * Copyright (C) Nodalink, SARL. 2013
   5  *
   6  * Author:
   7  *   Benoît Canet <benoit.canet@irqsave.net>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 or
  12  * (at your option) version 3 of the License.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23 #ifndef THROTTLE_H
  24 #define THROTTLE_H
  25
  26 #include <stdint.h>
  27 #include "qemu-common.h"
  28 #include "qemu/timer.h"
  29
  30 #define NANOSECONDS_PER_SECOND  1000000000.0
  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     QEMUTimer * timers[2];    /* timers used to do the throttling */
  69     QEMUClockType clock_type; /* the clock used */
  70
  71     /* Callbacks */
  72     QEMUTimerCB *read_timer_cb;
  73     QEMUTimerCB *write_timer_cb;
  74     void *timer_opaque;
  75 } ThrottleState;
  76
  77 /* operations on single leaky buckets */
  78 void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);
  79
  80 int64_t throttle_compute_wait(LeakyBucket *bkt);
  81
  82 /* expose timer computation function for unit tests */
  83 bool throttle_compute_timer(ThrottleState *ts,
  84                             bool is_write,
  85                             int64_t now,
  86                             int64_t *next_timestamp);
  87
  88 /* init/destroy cycle */
  89 void throttle_init(ThrottleState *ts,
  90                    AioContext *aio_context,
  91                    QEMUClockType clock_type,
  92                    void (read_timer)(void *),
  93                    void (write_timer)(void *),
  94                    void *timer_opaque);
  95
  96 void throttle_destroy(ThrottleState *ts);
  97
  98 void throttle_detach_aio_context(ThrottleState *ts);
  99
 100 void throttle_attach_aio_context(ThrottleState *ts, AioContext *new_context);
 101
 102 bool throttle_have_timer(ThrottleState *ts);
 103
 104 /* configuration */
 105 bool throttle_enabled(ThrottleConfig *cfg);
 106
 107 bool throttle_conflicting(ThrottleConfig *cfg);
 108
 109 bool throttle_is_valid(ThrottleConfig *cfg);
 110
 111 void throttle_config(ThrottleState *ts, ThrottleConfig *cfg);
 112
 113 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
 114
 115 /* usage */
 116 bool throttle_schedule_timer(ThrottleState *ts, bool is_write);
 117
 118 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
 119
 120 #endif