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5ddfffbdc5
Implement the continuous leaky bucket algorithm devised on IRC as a separate module. Signed-off-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
111 lines
3.4 KiB
C
111 lines
3.4 KiB
C
/*
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* QEMU throttling infrastructure
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*
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* Copyright (C) Nodalink, SARL. 2013
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*
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* Author:
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* Benoît Canet <benoit.canet@irqsave.net>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 or
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* (at your option) version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef THROTTLE_H
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#define THROTTLE_H
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#include <stdint.h>
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#include "qemu-common.h"
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#include "qemu/timer.h"
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#define NANOSECONDS_PER_SECOND 1000000000.0
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typedef enum {
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THROTTLE_BPS_TOTAL,
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THROTTLE_BPS_READ,
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THROTTLE_BPS_WRITE,
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THROTTLE_OPS_TOTAL,
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THROTTLE_OPS_READ,
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THROTTLE_OPS_WRITE,
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BUCKETS_COUNT,
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} BucketType;
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/*
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* The max parameter of the leaky bucket throttling algorithm can be used to
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* allow the guest to do bursts.
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* The max value is a pool of I/O that the guest can use without being throttled
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* at all. Throttling is triggered once this pool is empty.
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*/
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typedef struct LeakyBucket {
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double avg; /* average goal in units per second */
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double max; /* leaky bucket max burst in units */
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double level; /* bucket level in units */
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} LeakyBucket;
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/* The following structure is used to configure a ThrottleState
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* It contains a bit of state: the bucket field of the LeakyBucket structure.
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* However it allows to keep the code clean and the bucket field is reset to
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* zero at the right time.
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*/
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typedef struct ThrottleConfig {
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LeakyBucket buckets[BUCKETS_COUNT]; /* leaky buckets */
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uint64_t op_size; /* size of an operation in bytes */
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} ThrottleConfig;
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typedef struct ThrottleState {
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ThrottleConfig cfg; /* configuration */
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int64_t previous_leak; /* timestamp of the last leak done */
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QEMUTimer * timers[2]; /* timers used to do the throttling */
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QEMUClockType clock_type; /* the clock used */
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} ThrottleState;
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/* operations on single leaky buckets */
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void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);
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int64_t throttle_compute_wait(LeakyBucket *bkt);
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/* expose timer computation function for unit tests */
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bool throttle_compute_timer(ThrottleState *ts,
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bool is_write,
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int64_t now,
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int64_t *next_timestamp);
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/* init/destroy cycle */
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void throttle_init(ThrottleState *ts,
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QEMUClockType clock_type,
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void (read_timer)(void *),
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void (write_timer)(void *),
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void *timer_opaque);
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void throttle_destroy(ThrottleState *ts);
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bool throttle_have_timer(ThrottleState *ts);
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/* configuration */
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bool throttle_enabled(ThrottleConfig *cfg);
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bool throttle_conflicting(ThrottleConfig *cfg);
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bool throttle_is_valid(ThrottleConfig *cfg);
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void throttle_config(ThrottleState *ts, ThrottleConfig *cfg);
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void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
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/* usage */
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bool throttle_schedule_timer(ThrottleState *ts, bool is_write);
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void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
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#endif
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