Commit 0f3457f6 authored by Tejun Heo's avatar Tejun Heo
Browse files

blk-throttle: add backlink pointer from throtl_grp to throtl_data 



Add throtl_grp->td so that the td (throtl_data) a given tg
(throtl_grp) belongs to can be determined, and remove @td argument
from functions which take both @td and @tg as the former now can be
determined from the latter.

This generally simplifies the code and removes a number of cases where
@td is passed as an argument without being actually used.  This will
also help hierarchy support implementation.

While at it, in multi-line conditions, move the logical operators
leading broken lines to the end of the previous line.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
parent 5b2c16aa

block/blk-throttle.c

+53 −53
Original line number Diff line number Diff line
@@ -57,6 +57,9 @@ struct throtl_grp { 
	/* active throtl group service_queue member */

	struct rb_node rb_node;



	/* throtl_data this group belongs to */

	struct throtl_data *td;



	/*

	 * Dispatch time in jiffies. This is the estimated time when group

	 * will unthrottle and is ready to dispatch more bio. It is used as
@@ -140,11 +143,11 @@ static inline struct throtl_grp *td_root_tg(struct throtl_data *td) 
	return blkg_to_tg(td->queue->root_blkg);

}



#define throtl_log_tg(td, tg, fmt, args...)	do {			\

#define throtl_log_tg(tg, fmt, args...)	do {				\

	char __pbuf[128];						\

									\

	blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf));		\

	blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \

	blk_add_trace_msg((tg)->td->queue, "throtl %s " fmt, __pbuf, ##args); \

} while (0)



#define throtl_log(td, fmt, args...)	\
@@ -193,6 +196,7 @@ static void throtl_pd_init(struct blkcg_gq *blkg) 
	unsigned long flags;



	RB_CLEAR_NODE(&tg->rb_node);

	tg->td = blkg->q->td;

	bio_list_init(&tg->bio_lists[0]);

	bio_list_init(&tg->bio_lists[1]);
@@ -401,36 +405,34 @@ static void throtl_schedule_next_dispatch(struct throtl_data *td) 
		throtl_schedule_delayed_work(td, sq->first_pending_disptime - jiffies);

}



static inline void

throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)

static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)

{

	tg->bytes_disp[rw] = 0;

	tg->io_disp[rw] = 0;

	tg->slice_start[rw] = jiffies;

	tg->slice_end[rw] = jiffies + throtl_slice;

	throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",

	throtl_log_tg(tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",

			rw == READ ? 'R' : 'W', tg->slice_start[rw],

			tg->slice_end[rw], jiffies);

}



static inline void throtl_set_slice_end(struct throtl_data *td,

		struct throtl_grp *tg, bool rw, unsigned long jiffy_end)

static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,

					unsigned long jiffy_end)

{

	tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);

}



static inline void throtl_extend_slice(struct throtl_data *td,

		struct throtl_grp *tg, bool rw, unsigned long jiffy_end)

static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,

				       unsigned long jiffy_end)

{

	tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);

	throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",

	throtl_log_tg(tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",

			rw == READ ? 'R' : 'W', tg->slice_start[rw],

			tg->slice_end[rw], jiffies);

}



/* Determine if previously allocated or extended slice is complete or not */

static bool

throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)

static bool throtl_slice_used(struct throtl_grp *tg, bool rw)

{

	if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))

		return 0;
@@ -439,8 +441,7 @@ throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw) 
}



/* Trim the used slices and adjust slice start accordingly */

static inline void

throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)

static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)

{

	unsigned long nr_slices, time_elapsed, io_trim;

	u64 bytes_trim, tmp;
@@ -452,7 +453,7 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) 
	 * renewed. Don't try to trim the slice if slice is used. A new

	 * slice will start when appropriate.

	 */

	if (throtl_slice_used(td, tg, rw))

	if (throtl_slice_used(tg, rw))

		return;



	/*
@@ -463,7 +464,7 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) 
	 * is bad because it does not allow new slice to start.

	 */



	throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);

	throtl_set_slice_end(tg, rw, jiffies + throtl_slice);



	time_elapsed = jiffies - tg->slice_start[rw];
@@ -492,14 +493,14 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) 


	tg->slice_start[rw] += nr_slices * throtl_slice;



	throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"

	throtl_log_tg(tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"

			" start=%lu end=%lu jiffies=%lu",

			rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,

			tg->slice_start[rw], tg->slice_end[rw], jiffies);

}



static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,

		struct bio *bio, unsigned long *wait)

static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,

				  unsigned long *wait)

{

	bool rw = bio_data_dir(bio);

	unsigned int io_allowed;
@@ -548,8 +549,8 @@ static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg, 
	return 0;

}



static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,

		struct bio *bio, unsigned long *wait)

static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,

				 unsigned long *wait)

{

	bool rw = bio_data_dir(bio);

	u64 bytes_allowed, extra_bytes, tmp;
@@ -600,8 +601,8 @@ static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) { 
 * Returns whether one can dispatch a bio or not. Also returns approx number

 * of jiffies to wait before this bio is with-in IO rate and can be dispatched

 */

static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,

				struct bio *bio, unsigned long *wait)

static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,

			    unsigned long *wait)

{

	bool rw = bio_data_dir(bio);

	unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
@@ -626,15 +627,15 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, 
	 * existing slice to make sure it is at least throtl_slice interval

	 * long since now.

	 */

	if (throtl_slice_used(td, tg, rw))

		throtl_start_new_slice(td, tg, rw);

	if (throtl_slice_used(tg, rw))

		throtl_start_new_slice(tg, rw);

	else {

		if (time_before(tg->slice_end[rw], jiffies + throtl_slice))

			throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);

			throtl_extend_slice(tg, rw, jiffies + throtl_slice);

	}



	if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)

	    && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {

	if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&

	    tg_with_in_iops_limit(tg, bio, &iops_wait)) {

		if (wait)

			*wait = 0;

		return 1;
@@ -646,7 +647,7 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, 
		*wait = max_wait;



	if (time_before(tg->slice_end[rw], jiffies + max_wait))

		throtl_extend_slice(td, tg, rw, jiffies + max_wait);

		throtl_extend_slice(tg, rw, jiffies + max_wait);



	return 0;

}
@@ -707,10 +708,10 @@ static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg) 
	struct bio *bio;



	if ((bio = bio_list_peek(&tg->bio_lists[READ])))

		tg_may_dispatch(td, tg, bio, &read_wait);

		tg_may_dispatch(tg, bio, &read_wait);



	if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))

		tg_may_dispatch(td, tg, bio, &write_wait);

		tg_may_dispatch(tg, bio, &write_wait);



	min_wait = min(read_wait, write_wait);

	disptime = jiffies + min_wait;
@@ -721,8 +722,8 @@ static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg) 
	throtl_enqueue_tg(td, tg);

}



static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,

				bool rw, struct bio_list *bl)

static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,

				struct bio_list *bl)

{

	struct bio *bio;
@@ -731,18 +732,17 @@ static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg, 
	/* Drop bio reference on blkg */

	blkg_put(tg_to_blkg(tg));



	BUG_ON(td->nr_queued[rw] <= 0);

	td->nr_queued[rw]--;

	BUG_ON(tg->td->nr_queued[rw] <= 0);

	tg->td->nr_queued[rw]--;



	throtl_charge_bio(tg, bio);

	bio_list_add(bl, bio);

	bio->bi_rw |= REQ_THROTTLED;



	throtl_trim_slice(td, tg, rw);

	throtl_trim_slice(tg, rw);

}



static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,

				struct bio_list *bl)

static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)

{

	unsigned int nr_reads = 0, nr_writes = 0;

	unsigned int max_nr_reads = throtl_grp_quantum*3/4;
@@ -751,20 +751,20 @@ static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg, 


	/* Try to dispatch 75% READS and 25% WRITES */



	while ((bio = bio_list_peek(&tg->bio_lists[READ]))

		&& tg_may_dispatch(td, tg, bio, NULL)) {

	while ((bio = bio_list_peek(&tg->bio_lists[READ])) &&

	       tg_may_dispatch(tg, bio, NULL)) {



		tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);

		tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);

		nr_reads++;



		if (nr_reads >= max_nr_reads)

			break;

	}



	while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))

		&& tg_may_dispatch(td, tg, bio, NULL)) {

	while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) &&

	       tg_may_dispatch(tg, bio, NULL)) {



		tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);

		tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);

		nr_writes++;



		if (nr_writes >= max_nr_writes)
@@ -791,7 +791,7 @@ static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl) 


		throtl_dequeue_tg(td, tg);



		nr_disp += throtl_dispatch_tg(td, tg, bl);

		nr_disp += throtl_dispatch_tg(tg, bl);



		if (tg->nr_queued[0] || tg->nr_queued[1])

			tg_update_disptime(td, tg);
@@ -933,7 +933,7 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, 
	else

		*(unsigned int *)((void *)tg + cft->private) = ctx.v;



	throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",

	throtl_log_tg(tg, "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",

		      tg->bps[READ], tg->bps[WRITE],

		      tg->iops[READ], tg->iops[WRITE]);
@@ -945,8 +945,8 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, 
	 * that a group's limit are dropped suddenly and we don't want to

	 * account recently dispatched IO with new low rate.

	 */

	throtl_start_new_slice(td, tg, 0);

	throtl_start_new_slice(td, tg, 1);

	throtl_start_new_slice(tg, 0);

	throtl_start_new_slice(tg, 1);



	if (tg->flags & THROTL_TG_PENDING) {

		tg_update_disptime(td, tg);
@@ -1076,7 +1076,7 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) 
	}



	/* Bio is with-in rate limit of group */

	if (tg_may_dispatch(td, tg, bio, NULL)) {

	if (tg_may_dispatch(tg, bio, NULL)) {

		throtl_charge_bio(tg, bio);



		/*
@@ -1090,12 +1090,12 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) 
		 *

		 * So keep on trimming slice even if bio is not queued.

		 */

		throtl_trim_slice(td, tg, rw);

		throtl_trim_slice(tg, rw);

		goto out_unlock;

	}



queue_bio:

	throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"

	throtl_log_tg(tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"

			" iodisp=%u iops=%u queued=%d/%d",

			rw == READ ? 'R' : 'W',

			tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
@@ -1142,9 +1142,9 @@ void blk_throtl_drain(struct request_queue *q) 
		throtl_dequeue_tg(td, tg);



		while ((bio = bio_list_peek(&tg->bio_lists[READ])))

			tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);

			tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);

		while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))

			tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);

			tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);

	}

	spin_unlock_irq(q->queue_lock);

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