Release 4.18 block/blk-wbt.h

/* SPDX-License-Identifier: GPL-2.0 */
#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 */
	
WBT_DISCARD		= 8,	/* discard */

	
WBT_NR_BITS		= 4,	/* number of bits */
};


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

/*
 * 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,
};


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;

	
short enable_state;			/* WBT_STATE_* */

	/*
         * 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 */

	
struct blk_stat_callback *cb;

	
u64 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;
	
struct request_queue *queue;
	
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;
}

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#ifdef CONFIG_BLK_WBT



static inline void wbt_track(struct request *rq, enum wbt_flags flags)
{
	rq->wbt_flags |= flags;
}

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

void wbt_set_queue_depth(struct rq_wb *, unsigned int);
void wbt_set_write_cache(struct rq_wb *, bool);

u64 wbt_default_latency_nsec(struct request_queue *);

#else



static inline void wbt_track(struct request *rq, enum wbt_flags flags)
{
}
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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)
{
	return -EINVAL;
}
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static inline void wbt_exit(struct request_queue *q)
{
}
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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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static inline void wbt_issue(struct rq_wb *rwb, struct request *rq)
{
}
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static inline void wbt_disable_default(struct request_queue *q)
{
}
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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)
{
}
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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
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