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/*-
* Copyright (c) 2014-2019 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
typedef enum {
WT_THROTTLE_CKPT, /* Checkpoint throttle */
WT_THROTTLE_EVICT, /* Eviction throttle */
WT_THROTTLE_LOG, /* Logging throttle */
WT_THROTTLE_READ /* Read throttle */
} WT_THROTTLE_TYPE;
#define WT_THROTTLE_MIN WT_MEGABYTE /* Config minimum size */
/*
* The per-file threshold means we won't start the background fsync on a file until it crosses the
* per-file threshold of data written. The other minimum threshold defines a minimum threshold for
* the background thread. Otherwise we compute a percentage of the given capacity.
*/
#define WT_CAPACITY_FILE_THRESHOLD (WT_MEGABYTE / 2)
#define WT_CAPACITY_MIN_THRESHOLD (10 * WT_MEGABYTE)
#define WT_CAPACITY_PCT 10
/*
* If we're being asked to sleep a short amount of time, ignore it. A non-zero value means there may
* be a temporary violation of the capacity limitation, but one that would even out. That is,
* possibly fewer sleeps with the risk of more choppy behavior as this number is larger.
*/
#define WT_CAPACITY_SLEEP_CUTOFF_US 100
/*
* When given a total capacity, divide it up for each subsystem. These defines represent the
* percentage of the total capacity that we allow for each subsystem capacity. We allow and expect
* the sum of the subsystems to exceed 100, as often they are not at their maximum at the same time.
* In any event, we track the total capacity separately, so it is never exceeded.
*/
#define WT_CAPACITY_SYS(total, pct) ((total) * (pct) / 100)
#define WT_CAP_CKPT 5
#define WT_CAP_EVICT 50
#define WT_CAP_LOG 30
#define WT_CAP_READ 55
struct __wt_capacity {
uint64_t ckpt; /* Bytes/sec checkpoint capacity */
uint64_t evict; /* Bytes/sec eviction capacity */
uint64_t log; /* Bytes/sec logging capacity */
uint64_t read; /* Bytes/sec read capacity */
uint64_t total; /* Bytes/sec total capacity */
uint64_t threshold; /* Capacity size period */
volatile uint64_t written; /* Written this period */
volatile bool signalled; /* Capacity signalled */
/*
* A reservation is a point in time when a read or write for a subsystem can be scheduled, so as
* not to overrun the given capacity. These values hold the next available reservation, in
* nanoseconds since the epoch. Getting a reservation with a future time implies sleeping until
* that time; getting a reservation with a past time implies that the operation can be done
* immediately.
*/
uint64_t reservation_ckpt; /* Atomic: next checkpoint write */
uint64_t reservation_evict; /* Atomic: next eviction write */
uint64_t reservation_log; /* Atomic: next logging write */
uint64_t reservation_read; /* Atomic: next read */
uint64_t reservation_total; /* Atomic: next operation of any kind */
};
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