[linux-block.git] / block / blk-throttle.h

#ifndef BLK_THROTTLE_H
#define BLK_THROTTLE_H

#include "blk-cgroup-rwstat.h"

/*
 * To implement hierarchical throttling, throtl_grps form a tree and bios
 * are dispatched upwards level by level until they reach the top and get
 * issued.  When dispatching bios from the children and local group at each
 * level, if the bios are dispatched into a single bio_list, there's a risk
 * of a local or child group which can queue many bios at once filling up
 * the list starving others.
 *
 * To avoid such starvation, dispatched bios are queued separately
 * according to where they came from.  When they are again dispatched to
 * the parent, they're popped in round-robin order so that no single source
 * hogs the dispatch window.
 *
 * throtl_qnode is used to keep the queued bios separated by their sources.
 * Bios are queued to throtl_qnode which in turn is queued to
 * throtl_service_queue and then dispatched in round-robin order.
 *
 * It's also used to track the reference counts on blkg's.  A qnode always
 * belongs to a throtl_grp and gets queued on itself or the parent, so
 * incrementing the reference of the associated throtl_grp when a qnode is
 * queued and decrementing when dequeued is enough to keep the whole blkg
 * tree pinned while bios are in flight.
 */
struct throtl_qnode {
	struct list_head	node;		/* service_queue->queued[] */
	struct bio_list		bios;		/* queued bios */
	struct throtl_grp	*tg;		/* tg this qnode belongs to */
};

struct throtl_service_queue {
	struct throtl_service_queue *parent_sq;	/* the parent service_queue */

	/*
	 * Bios queued directly to this service_queue or dispatched from
	 * children throtl_grp's.
	 */
	struct list_head	queued[2];	/* throtl_qnode [READ/WRITE] */
	unsigned int		nr_queued[2];	/* number of queued bios */

	/*
	 * RB tree of active children throtl_grp's, which are sorted by
	 * their ->disptime.
	 */
	struct rb_root_cached	pending_tree;	/* RB tree of active tgs */
	unsigned int		nr_pending;	/* # queued in the tree */
	unsigned long		first_pending_disptime;	/* disptime of the first tg */
	struct timer_list	pending_timer;	/* fires on first_pending_disptime */
};

enum tg_state_flags {
	THROTL_TG_PENDING	= 1 << 0,	/* on parent's pending tree */
	THROTL_TG_WAS_EMPTY	= 1 << 1,	/* bio_lists[] became non-empty */
	THROTL_TG_HAS_IOPS_LIMIT = 1 << 2,	/* tg has iops limit */
};

enum {
	LIMIT_LOW,
	LIMIT_MAX,
	LIMIT_CNT,
};

struct throtl_grp {
	/* must be the first member */
	struct blkg_policy_data pd;

	/* active throtl group service_queue member */
	struct rb_node rb_node;

	/* throtl_data this group belongs to */
	struct throtl_data *td;

	/* this group's service queue */
	struct throtl_service_queue service_queue;

	/*
	 * qnode_on_self is used when bios are directly queued to this
	 * throtl_grp so that local bios compete fairly with bios
	 * dispatched from children.  qnode_on_parent is used when bios are
	 * dispatched from this throtl_grp into its parent and will compete
	 * with the sibling qnode_on_parents and the parent's
	 * qnode_on_self.
	 */
	struct throtl_qnode qnode_on_self[2];
	struct throtl_qnode qnode_on_parent[2];

	/*
	 * Dispatch time in jiffies. This is the estimated time when group
	 * will unthrottle and is ready to dispatch more bio. It is used as
	 * key to sort active groups in service tree.
	 */
	unsigned long disptime;

	unsigned int flags;

	/* are there any throtl rules between this group and td? */
	bool has_rules[2];

	/* internally used bytes per second rate limits */
	uint64_t bps[2][LIMIT_CNT];
	/* user configured bps limits */
	uint64_t bps_conf[2][LIMIT_CNT];

	/* internally used IOPS limits */
	unsigned int iops[2][LIMIT_CNT];
	/* user configured IOPS limits */
	unsigned int iops_conf[2][LIMIT_CNT];

	/* Number of bytes dispatched in current slice */
	uint64_t bytes_disp[2];
	/* Number of bio's dispatched in current slice */
	unsigned int io_disp[2];

	unsigned long last_low_overflow_time[2];

	uint64_t last_bytes_disp[2];
	unsigned int last_io_disp[2];

	unsigned long last_check_time;

	unsigned long latency_target; /* us */
	unsigned long latency_target_conf; /* us */
	/* When did we start a new slice */
	unsigned long slice_start[2];
	unsigned long slice_end[2];

	unsigned long last_finish_time; /* ns / 1024 */
	unsigned long checked_last_finish_time; /* ns / 1024 */
	unsigned long avg_idletime; /* ns / 1024 */
	unsigned long idletime_threshold; /* us */
	unsigned long idletime_threshold_conf; /* us */

	unsigned int bio_cnt; /* total bios */
	unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
	unsigned long bio_cnt_reset_time;

	struct blkg_rwstat stat_bytes;
	struct blkg_rwstat stat_ios;
};

extern struct blkcg_policy blkcg_policy_throtl;

static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
{
	return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
}

static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
{
	return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
}

/*
 * Internal throttling interface
 */
#ifndef CONFIG_BLK_DEV_THROTTLING
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
static inline void blk_throtl_register_queue(struct request_queue *q) { }
static inline bool blk_throtl_bio(struct bio *bio) { return false; }
#else /* CONFIG_BLK_DEV_THROTTLING */
int blk_throtl_init(struct request_queue *q);
void blk_throtl_exit(struct request_queue *q);
void blk_throtl_register_queue(struct request_queue *q);
bool __blk_throtl_bio(struct bio *bio);
static inline bool blk_throtl_bio(struct bio *bio)
{
	struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);

	/* no need to throttle bps any more if the bio has been throttled */
	if (bio_flagged(bio, BIO_THROTTLED) &&
	    !(tg->flags & THROTL_TG_HAS_IOPS_LIMIT))
		return false;

	if (!tg->has_rules[bio_data_dir(bio)])
		return false;

	return __blk_throtl_bio(bio);
}
#endif /* CONFIG_BLK_DEV_THROTTLING */

#endif
Commit	Line	Data
a7b36ee6 JA	1	#ifndef BLK_THROTTLE_H
	2	#define BLK_THROTTLE_H
	3
	4	#include "blk-cgroup-rwstat.h"
	5
	6	/*
	7	* To implement hierarchical throttling, throtl_grps form a tree and bios
	8	* are dispatched upwards level by level until they reach the top and get
	9	* issued. When dispatching bios from the children and local group at each
	10	* level, if the bios are dispatched into a single bio_list, there's a risk
	11	* of a local or child group which can queue many bios at once filling up
	12	* the list starving others.
	13	*
	14	* To avoid such starvation, dispatched bios are queued separately
	15	* according to where they came from. When they are again dispatched to
	16	* the parent, they're popped in round-robin order so that no single source
	17	* hogs the dispatch window.
	18	*
	19	* throtl_qnode is used to keep the queued bios separated by their sources.
	20	* Bios are queued to throtl_qnode which in turn is queued to
	21	* throtl_service_queue and then dispatched in round-robin order.
	22	*
	23	* It's also used to track the reference counts on blkg's. A qnode always
	24	* belongs to a throtl_grp and gets queued on itself or the parent, so
	25	* incrementing the reference of the associated throtl_grp when a qnode is
	26	* queued and decrementing when dequeued is enough to keep the whole blkg
	27	* tree pinned while bios are in flight.
	28	*/
	29	struct throtl_qnode {
	30	struct list_head node; /* service_queue->queued[] */
	31	struct bio_list bios; /* queued bios */
	32	struct throtl_grp tg; / tg this qnode belongs to */
	33	};
	34
	35	struct throtl_service_queue {
	36	struct throtl_service_queue parent_sq; / the parent service_queue */
	37
	38	/*
	39	* Bios queued directly to this service_queue or dispatched from
	40	* children throtl_grp's.
	41	*/
	42	struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */
	43	unsigned int nr_queued[2]; /* number of queued bios */
	44
	45	/*
	46	* RB tree of active children throtl_grp's, which are sorted by
	47	* their ->disptime.
	48	*/
	49	struct rb_root_cached pending_tree; /* RB tree of active tgs */
	50	unsigned int nr_pending; /* # queued in the tree */
	51	unsigned long first_pending_disptime; /* disptime of the first tg */
	52	struct timer_list pending_timer; /* fires on first_pending_disptime */
	53	};
	54
5a93b602 ML	55	enum tg_state_flags {
	56	THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
	57	THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
	58	THROTL_TG_HAS_IOPS_LIMIT = 1 << 2, /* tg has iops limit */
	59	};
	60
a7b36ee6 JA	61	enum {
	62	LIMIT_LOW,
	63	LIMIT_MAX,
	64	LIMIT_CNT,
	65	};
	66
	67	struct throtl_grp {
	68	/* must be the first member */
	69	struct blkg_policy_data pd;
	70
	71	/* active throtl group service_queue member */
	72	struct rb_node rb_node;
	73
	74	/* throtl_data this group belongs to */
	75	struct throtl_data *td;
	76
	77	/* this group's service queue */
	78	struct throtl_service_queue service_queue;
	79
	80	/*
	81	* qnode_on_self is used when bios are directly queued to this
	82	* throtl_grp so that local bios compete fairly with bios
	83	* dispatched from children. qnode_on_parent is used when bios are
	84	* dispatched from this throtl_grp into its parent and will compete
	85	* with the sibling qnode_on_parents and the parent's
	86	* qnode_on_self.
	87	*/
	88	struct throtl_qnode qnode_on_self[2];
	89	struct throtl_qnode qnode_on_parent[2];
	90
	91	/*
	92	* Dispatch time in jiffies. This is the estimated time when group
	93	* will unthrottle and is ready to dispatch more bio. It is used as
	94	* key to sort active groups in service tree.
	95	*/
	96	unsigned long disptime;
	97
	98	unsigned int flags;
	99
	100	/* are there any throtl rules between this group and td? */
	101	bool has_rules[2];
	102
	103	/* internally used bytes per second rate limits */
	104	uint64_t bps[2][LIMIT_CNT];
	105	/* user configured bps limits */
	106	uint64_t bps_conf[2][LIMIT_CNT];
	107
	108	/* internally used IOPS limits */
	109	unsigned int iops[2][LIMIT_CNT];
	110	/* user configured IOPS limits */
	111	unsigned int iops_conf[2][LIMIT_CNT];
	112
	113	/* Number of bytes dispatched in current slice */
	114	uint64_t bytes_disp[2];
	115	/* Number of bio's dispatched in current slice */
	116	unsigned int io_disp[2];
	117
	118	unsigned long last_low_overflow_time[2];
	119
	120	uint64_t last_bytes_disp[2];
	121	unsigned int last_io_disp[2];
	122
	123	unsigned long last_check_time;
	124
125	unsigned long latency_target; /* us */
126	unsigned long latency_target_conf; /* us */
127	/* When did we start a new slice */
128	unsigned long slice_start[2];
129	unsigned long slice_end[2];
130
131	unsigned long last_finish_time; /* ns / 1024 */
132	unsigned long checked_last_finish_time; /* ns / 1024 */
133	unsigned long avg_idletime; /* ns / 1024 */
134	unsigned long idletime_threshold; /* us */
135	unsigned long idletime_threshold_conf; /* us */
136
137	unsigned int bio_cnt; /* total bios */
138	unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
139	unsigned long bio_cnt_reset_time;
140
a7b36ee6 JA	141	struct blkg_rwstat stat_bytes;
	142	struct blkg_rwstat stat_ios;
	143	};
	144
	145	extern struct blkcg_policy blkcg_policy_throtl;
	146
	147	static inline struct throtl_grp pd_to_tg(struct blkg_policy_data pd)
	148	{
	149	return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
	150	}
	151
	152	static inline struct throtl_grp blkg_to_tg(struct blkcg_gq blkg)
	153	{
	154	return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
	155	}
	156
	157	/*
	158	* Internal throttling interface
	159	*/
	160	#ifndef CONFIG_BLK_DEV_THROTTLING
	161	static inline int blk_throtl_init(struct request_queue *q) { return 0; }
	162	static inline void blk_throtl_exit(struct request_queue *q) { }
	163	static inline void blk_throtl_register_queue(struct request_queue *q) { }
a7b36ee6 JA	164	static inline bool blk_throtl_bio(struct bio *bio) { return false; }
	165	#else /* CONFIG_BLK_DEV_THROTTLING */
	166	int blk_throtl_init(struct request_queue *q);
	167	void blk_throtl_exit(struct request_queue *q);
	168	void blk_throtl_register_queue(struct request_queue *q);
a7b36ee6 JA	169	bool __blk_throtl_bio(struct bio *bio);
	170	static inline bool blk_throtl_bio(struct bio *bio)
	171	{
	172	struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
	173
5a93b602 ML	174	/* no need to throttle bps any more if the bio has been throttled */
	175	if (bio_flagged(bio, BIO_THROTTLED) &&
	176	!(tg->flags & THROTL_TG_HAS_IOPS_LIMIT))
	177	return false;
	178
a7b36ee6 JA	179	if (!tg->has_rules[bio_data_dir(bio)])
	180	return false;
	181
	182	return __blk_throtl_bio(bio);
	183	}
	184	#endif /* CONFIG_BLK_DEV_THROTTLING */
	185
	186	#endif