Clock type in throttling is currently inferred by the ThrottleTimer's clock type even though it is a per-ThrottleGroup property; it doesn't make sense to have different clock types in the same group. Moving this to a field in ThrottleGroup can simplify some of the throttle functions. Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
158 lines
5.3 KiB
C
158 lines
5.3 KiB
C
/*
|
|
* QEMU throttling infrastructure
|
|
*
|
|
* Copyright (C) Nodalink, EURL. 2013-2014
|
|
* Copyright (C) Igalia, S.L. 2015-2016
|
|
*
|
|
* Authors:
|
|
* Benoît Canet <benoit.canet@nodalink.com>
|
|
* Alberto Garcia <berto@igalia.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 or
|
|
* (at your option) version 3 of the License.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef THROTTLE_H
|
|
#define THROTTLE_H
|
|
|
|
#include "qemu-common.h"
|
|
#include "qemu/timer.h"
|
|
|
|
#define THROTTLE_VALUE_MAX 1000000000000000LL
|
|
|
|
typedef enum {
|
|
THROTTLE_BPS_TOTAL,
|
|
THROTTLE_BPS_READ,
|
|
THROTTLE_BPS_WRITE,
|
|
THROTTLE_OPS_TOTAL,
|
|
THROTTLE_OPS_READ,
|
|
THROTTLE_OPS_WRITE,
|
|
BUCKETS_COUNT,
|
|
} BucketType;
|
|
|
|
/*
|
|
* This module implements I/O limits using the leaky bucket
|
|
* algorithm. The code is independent of the I/O units, but it is
|
|
* currently used for bytes per second and operations per second.
|
|
*
|
|
* Three parameters can be set by the user:
|
|
*
|
|
* - avg: the desired I/O limits in units per second.
|
|
* - max: the limit during bursts, also in units per second.
|
|
* - burst_length: the maximum length of the burst period, in seconds.
|
|
*
|
|
* Here's how it works:
|
|
*
|
|
* - The bucket level (number of performed I/O units) is kept in
|
|
* bkt.level and leaks at a rate of bkt.avg units per second.
|
|
*
|
|
* - The size of the bucket is bkt.max * bkt.burst_length. Once the
|
|
* bucket is full no more I/O is performed until the bucket leaks
|
|
* again. This is what makes the I/O rate bkt.avg.
|
|
*
|
|
* - The bkt.avg rate does not apply until the bucket is full,
|
|
* allowing the user to do bursts until then. The I/O limit during
|
|
* bursts is bkt.max. To enforce this limit we keep an additional
|
|
* bucket in bkt.burst_length that leaks at a rate of bkt.max units
|
|
* per second.
|
|
*
|
|
* - Because of all of the above, the user can perform I/O at a
|
|
* maximum of bkt.max units per second for at most bkt.burst_length
|
|
* seconds in a row. After that the bucket will be full and the I/O
|
|
* rate will go down to bkt.avg.
|
|
*
|
|
* - Since the bucket always leaks at a rate of bkt.avg, this also
|
|
* determines how much the user needs to wait before being able to
|
|
* do bursts again.
|
|
*/
|
|
|
|
typedef struct LeakyBucket {
|
|
double avg; /* average goal in units per second */
|
|
double max; /* leaky bucket max burst in units */
|
|
double level; /* bucket level in units */
|
|
double burst_level; /* bucket level in units (for computing bursts) */
|
|
unsigned burst_length; /* max length of the burst period, in seconds */
|
|
} LeakyBucket;
|
|
|
|
/* The following structure is used to configure a ThrottleState
|
|
* It contains a bit of state: the bucket field of the LeakyBucket structure.
|
|
* However it allows to keep the code clean and the bucket field is reset to
|
|
* zero at the right time.
|
|
*/
|
|
typedef struct ThrottleConfig {
|
|
LeakyBucket buckets[BUCKETS_COUNT]; /* leaky buckets */
|
|
uint64_t op_size; /* size of an operation in bytes */
|
|
} ThrottleConfig;
|
|
|
|
typedef struct ThrottleState {
|
|
ThrottleConfig cfg; /* configuration */
|
|
int64_t previous_leak; /* timestamp of the last leak done */
|
|
} ThrottleState;
|
|
|
|
typedef struct ThrottleTimers {
|
|
QEMUTimer *timers[2]; /* timers used to do the throttling */
|
|
QEMUClockType clock_type; /* the clock used */
|
|
|
|
/* Callbacks */
|
|
QEMUTimerCB *read_timer_cb;
|
|
QEMUTimerCB *write_timer_cb;
|
|
void *timer_opaque;
|
|
} ThrottleTimers;
|
|
|
|
/* operations on single leaky buckets */
|
|
void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);
|
|
|
|
int64_t throttle_compute_wait(LeakyBucket *bkt);
|
|
|
|
/* init/destroy cycle */
|
|
void throttle_init(ThrottleState *ts);
|
|
|
|
void throttle_timers_init(ThrottleTimers *tt,
|
|
AioContext *aio_context,
|
|
QEMUClockType clock_type,
|
|
QEMUTimerCB *read_timer_cb,
|
|
QEMUTimerCB *write_timer_cb,
|
|
void *timer_opaque);
|
|
|
|
void throttle_timers_destroy(ThrottleTimers *tt);
|
|
|
|
void throttle_timers_detach_aio_context(ThrottleTimers *tt);
|
|
|
|
void throttle_timers_attach_aio_context(ThrottleTimers *tt,
|
|
AioContext *new_context);
|
|
|
|
bool throttle_timers_are_initialized(ThrottleTimers *tt);
|
|
|
|
/* configuration */
|
|
bool throttle_enabled(ThrottleConfig *cfg);
|
|
|
|
bool throttle_is_valid(ThrottleConfig *cfg, Error **errp);
|
|
|
|
void throttle_config(ThrottleState *ts,
|
|
QEMUClockType clock_type,
|
|
ThrottleTimers *tt,
|
|
ThrottleConfig *cfg);
|
|
|
|
void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
|
|
|
|
void throttle_config_init(ThrottleConfig *cfg);
|
|
|
|
/* usage */
|
|
bool throttle_schedule_timer(ThrottleState *ts,
|
|
ThrottleTimers *tt,
|
|
bool is_write);
|
|
|
|
void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
|
|
|
|
#endif
|