/* SPDX-License-Identifier: GPL-2.0 */ #ifndef BLK_STAT_H #define BLK_STAT_H #include <linux/kernel.h> #include <linux/blkdev.h> #include <linux/ktime.h> #include <linux/rcupdate.h> #include <linux/timer.h> /** * struct blk_stat_callback - Block statistics callback. * * A &struct blk_stat_callback is associated with a &struct request_queue. While * @timer is active, that queue's request completion latencies are sorted into * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked. */ struct blk_stat_callback { /* * @list: RCU list of callbacks for a &struct request_queue. */ struct list_head list; /** * @timer: Timer for the next callback invocation. */ struct timer_list timer; /** * @cpu_stat: Per-cpu statistics buckets. */ struct blk_rq_stat __percpu *cpu_stat; /** * @bucket_fn: Given a request, returns which statistics bucket it * should be accounted under. Return -1 for no bucket for this * request. */ int (*bucket_fn)(const struct request *); /** * @buckets: Number of statistics buckets. */ unsigned int buckets; /** * @stat: Array of statistics buckets. */ struct blk_rq_stat *stat; /** * @fn: Callback function. */ void (*timer_fn)(struct blk_stat_callback *); /** * @data: Private pointer for the user. */ void *data; struct rcu_head rcu; }; struct blk_queue_stats *blk_alloc_queue_stats(void); void blk_free_queue_stats(struct blk_queue_stats *); void blk_stat_add(struct request *rq, u64 now); /* record time/size info in request but not add a callback */ void blk_stat_enable_accounting(struct request_queue *q); /** * blk_stat_alloc_callback() - Allocate a block statistics callback. * @timer_fn: Timer callback function. * @bucket_fn: Bucket callback function. * @buckets: Number of statistics buckets. * @data: Value for the @data field of the &struct blk_stat_callback. * * See &struct blk_stat_callback for details on the callback functions. * * Return: &struct blk_stat_callback on success or NULL on ENOMEM. */ struct blk_stat_callback * blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), int (*bucket_fn)(const struct request *), unsigned int buckets, void *data); /** * blk_stat_add_callback() - Add a block statistics callback to be run on a * request queue. * @q: The request queue. * @cb: The callback. * * Note that a single &struct blk_stat_callback can only be added to a single * &struct request_queue. */ void blk_stat_add_callback(struct request_queue *q, struct blk_stat_callback *cb); /** * blk_stat_remove_callback() - Remove a block statistics callback from a * request queue. * @q: The request queue. * @cb: The callback. * * When this returns, the callback is not running on any CPUs and will not be * called again unless readded. */ void blk_stat_remove_callback(struct request_queue *q, struct blk_stat_callback *cb); /** * blk_stat_free_callback() - Free a block statistics callback. * @cb: The callback. * * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must * not be associated with a request queue. I.e., if it was previously added with * blk_stat_add_callback(), it must also have been removed since then with * blk_stat_remove_callback(). */ void blk_stat_free_callback(struct blk_stat_callback *cb); /** * blk_stat_is_active() - Check if a block statistics callback is currently * gathering statistics. * @cb: The callback. */ static inline bool blk_stat_is_active(struct blk_stat_callback *cb) { return timer_pending(&cb->timer); } /** * blk_stat_activate_nsecs() - Gather block statistics during a time window in * nanoseconds. * @cb: The callback. * @nsecs: Number of nanoseconds to gather statistics for. * * The timer callback will be called when the window expires. */ static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb, u64 nsecs) { mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs)); } /** * blk_stat_activate_msecs() - Gather block statistics during a time window in * milliseconds. * @cb: The callback. * @msecs: Number of milliseconds to gather statistics for. * * The timer callback will be called when the window expires. */ static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb, unsigned int msecs) { mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs)); } void blk_rq_stat_add(struct blk_rq_stat *, u64); void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *); void blk_rq_stat_init(struct blk_rq_stat *); #endif