block: move blk-throtl fast path inline

Even if no policies are defined, we spend ~2% of the total IO time
checking. Move the fast path inline.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -32,6 +32,7 @@
 #include <linux/psi.h>
 #include "blk.h"
 #include "blk-ioprio.h"
+#include "blk-throttle.h"
 
 /*
  * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.

block/blk-core.c

@@ -50,6 +50,7 @@
 #include "blk-mq.h"
 #include "blk-mq-sched.h"
 #include "blk-pm.h"
+#include "blk-throttle.h"
 
 struct dentry *blk_debugfs_root;
 

block/blk-merge.c

@@ -13,6 +13,7 @@
 
 #include "blk.h"
 #include "blk-rq-qos.h"
+#include "blk-throttle.h"
 
 static inline bool bio_will_gap(struct request_queue *q,
 		struct request *prev_rq, struct bio *prev, struct bio *next)

block/blk-sysfs.c

@@ -17,6 +17,7 @@
 #include "blk-mq.h"
 #include "blk-mq-debugfs.h"
 #include "blk-wbt.h"
+#include "blk-throttle.h"
 
 struct queue_sysfs_entry {
 	struct attribute attr;

block/blk-throttle.c

@@ -13,6 +13,7 @@
 #include <linux/blk-cgroup.h>
 #include "blk.h"
 #include "blk-cgroup-rwstat.h"
+#include "blk-throttle.h"
 
 /* Max dispatch from a group in 1 round */
 #define THROTL_GRP_QUANTUM 8
@@ -37,154 +38,16 @@
  */
 #define LATENCY_FILTERED_HD (1000L) /* 1ms */
 
-static struct blkcg_policy blkcg_policy_throtl;
-
 /* A workqueue to queue throttle related work */
 static struct workqueue_struct *kthrotld_workqueue;
 
-/*
- * 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 */
 };
 
 #define rb_entry_tg(node)	rb_entry((node), struct throtl_grp, rb_node)
 
-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;
-
-	atomic_t io_split_cnt[2];
-	atomic_t last_io_split_cnt[2];
-
-	struct blkg_rwstat stat_bytes;
-	struct blkg_rwstat stat_ios;
-};
-
 /* We measure latency for request size from <= 4k to >= 1M */
 #define LATENCY_BUCKET_SIZE 9
 
@@ -231,16 +94,6 @@ struct throtl_data
 
 static void throtl_pending_timer_fn(struct timer_list *t);
 
-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));
-}
-
 static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
 {
 	return pd_to_blkg(&tg->pd);
@@ -1794,7 +1647,7 @@ static void throtl_shutdown_wq(struct request_queue *q)
 	cancel_work_sync(&td->dispatch_work);
 }
 
-static struct blkcg_policy blkcg_policy_throtl = {
+struct blkcg_policy blkcg_policy_throtl = {
 	.dfl_cftypes		= throtl_files,
 	.legacy_cftypes		= throtl_legacy_files,
 
@@ -2208,7 +2061,7 @@ void blk_throtl_charge_bio_split(struct bio *bio)
 	} while (parent);
 }
 
-bool blk_throtl_bio(struct bio *bio)
+bool __blk_throtl_bio(struct bio *bio)
 {
 	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
 	struct blkcg_gq *blkg = bio->bi_blkg;
@@ -2221,19 +2074,12 @@ bool blk_throtl_bio(struct bio *bio)
 
 	rcu_read_lock();
 
-	/* see throtl_charge_bio() */
-	if (bio_flagged(bio, BIO_THROTTLED))
-		goto out;
-
 	if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
 		blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
 				bio->bi_iter.bi_size);
 		blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
 	}
 
-	if (!tg->has_rules[rw])
-		goto out;
-
 	spin_lock_irq(&q->queue_lock);
 
 	throtl_update_latency_buckets(td);
@@ -2317,7 +2163,6 @@ bool blk_throtl_bio(struct bio *bio)
 
 out_unlock:
 	spin_unlock_irq(&q->queue_lock);
-out:
 	bio_set_flag(bio, BIO_THROTTLED);
 
 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW