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 121