blk-wbt.h 3.7 KB
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef WB_THROTTLE_H
#define WB_THROTTLE_H

#include <linux/kernel.h>
#include <linux/atomic.h>
#include <linux/wait.h>
#include <linux/timer.h>
#include <linux/ktime.h>

#include "blk-stat.h"

enum wbt_flags {
	WBT_TRACKED		= 1,	/* write, tracked for throttling */
	WBT_READ		= 2,	/* read */
	WBT_KSWAPD		= 4,	/* write, from kswapd */
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	WBT_DISCARD		= 8,	/* discard */
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	WBT_NR_BITS		= 4,	/* number of bits */
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};

enum {
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	WBT_RWQ_BG		= 0,
	WBT_RWQ_KSWAPD,
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	WBT_RWQ_DISCARD,
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	WBT_NUM_RWQ,
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};

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/*
 * Enable states. Either off, or on by default (done at init time),
 * or on through manual setup in sysfs.
 */
enum {
	WBT_STATE_ON_DEFAULT	= 1,
	WBT_STATE_ON_MANUAL	= 2,
};

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struct rq_wait {
	wait_queue_head_t wait;
	atomic_t inflight;
};

struct rq_wb {
	/*
	 * Settings that govern how we throttle
	 */
	unsigned int wb_background;		/* background writeback */
	unsigned int wb_normal;			/* normal writeback */
	unsigned int wb_max;			/* max throughput writeback */
	int scale_step;
	bool scaled_max;

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	short enable_state;			/* WBT_STATE_* */

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	/*
	 * Number of consecutive periods where we don't have enough
	 * information to make a firm scale up/down decision.
	 */
	unsigned int unknown_cnt;

	u64 win_nsec;				/* default window size */
	u64 cur_win_nsec;			/* current window size */

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	struct blk_stat_callback *cb;
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	s64 sync_issue;
	void *sync_cookie;

	unsigned int wc;
	unsigned int queue_depth;

	unsigned long last_issue;		/* last non-throttled issue */
	unsigned long last_comp;		/* last non-throttled comp */
	unsigned long min_lat_nsec;
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	struct request_queue *queue;
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	struct rq_wait rq_wait[WBT_NUM_RWQ];
};

static inline unsigned int wbt_inflight(struct rq_wb *rwb)
{
	unsigned int i, ret = 0;

	for (i = 0; i < WBT_NUM_RWQ; i++)
		ret += atomic_read(&rwb->rq_wait[i].inflight);

	return ret;
}

#ifdef CONFIG_BLK_WBT

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static inline void wbt_track(struct request *rq, enum wbt_flags flags)
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{
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	rq->issue_stat.stat |= ((u64)flags) << BLK_STAT_RES_SHIFT;
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}

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void __wbt_done(struct rq_wb *, enum wbt_flags);
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void wbt_done(struct rq_wb *, struct request *);
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enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
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int wbt_init(struct request_queue *);
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void wbt_exit(struct request_queue *);
void wbt_update_limits(struct rq_wb *);
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void wbt_requeue(struct rq_wb *, struct request *);
void wbt_issue(struct rq_wb *, struct request *);
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void wbt_disable_default(struct request_queue *);
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void wbt_enable_default(struct request_queue *);
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void wbt_set_queue_depth(struct rq_wb *, unsigned int);
void wbt_set_write_cache(struct rq_wb *, bool);

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u64 wbt_default_latency_nsec(struct request_queue *);

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#else

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static inline void wbt_track(struct request *rq, enum wbt_flags flags)
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{
}
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static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
{
}
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static inline void wbt_done(struct rq_wb *rwb, struct request *rq)
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{
}
static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
				      spinlock_t *lock)
{
	return 0;
}
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static inline int wbt_init(struct request_queue *q)
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{
	return -EINVAL;
}
static inline void wbt_exit(struct request_queue *q)
{
}
static inline void wbt_update_limits(struct rq_wb *rwb)
{
}
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static inline void wbt_requeue(struct rq_wb *rwb, struct request *rq)
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{
}
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static inline void wbt_issue(struct rq_wb *rwb, struct request *rq)
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{
}
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static inline void wbt_disable_default(struct request_queue *q)
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{
}
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static inline void wbt_enable_default(struct request_queue *q)
{
}
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static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
{
}
static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc)
{
}
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static inline u64 wbt_default_latency_nsec(struct request_queue *q)
{
	return 0;
}
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#endif /* CONFIG_BLK_WBT */

#endif