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#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_CANCELING = 1 << 2, /* starts to cancel bio */
};
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_bps[2];
bool has_rules_iops[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];
/*
* The following two fields are updated when new configuration is
* submitted while some bios are still throttled, they record how many
* bytes/ios are waited already in previous configuration, and they will
* be used to calculate wait time under new configuration.
*/
uint64_t carryover_bytes[2];
unsigned int carryover_ios[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 gendisk *disk) { return 0; }
static inline void blk_throtl_exit(struct gendisk *disk) { }
static inline void blk_throtl_register(struct gendisk *disk) { }
static inline bool blk_throtl_bio(struct bio *bio) { return false; }
static inline void blk_throtl_cancel_bios(struct gendisk *disk) { }
#else /* CONFIG_BLK_DEV_THROTTLING */
int blk_throtl_init(struct gendisk *disk);
void blk_throtl_exit(struct gendisk *disk);
void blk_throtl_register(struct gendisk *disk);
bool __blk_throtl_bio(struct bio *bio);
void blk_throtl_cancel_bios(struct gendisk *disk);
static inline bool blk_should_throtl(struct bio *bio)
{
struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
int rw = bio_data_dir(bio);
/* iops limit is always counted */
if (tg->has_rules_iops[rw])
return true;
if (tg->has_rules_bps[rw] && !bio_flagged(bio, BIO_BPS_THROTTLED))
return true;
return false;
}
static inline bool blk_throtl_bio(struct bio *bio)
{
if (!blk_should_throtl(bio))
return false;
return __blk_throtl_bio(bio);
}
#endif /* CONFIG_BLK_DEV_THROTTLING */
#endif
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