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Commit 09663c86 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
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block/cfq: replace cfq_rb_root leftmost caching 

... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-11-dave@stgolabs.net


Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a23ba907

block/cfq-iosched.c

+20 −50
Original line number Diff line number Diff line
@@ -93,13 +93,12 @@ struct cfq_ttime { 
 * move this into the elevator for the rq sorting as well.

 */

struct cfq_rb_root {

	struct rb_root rb;

	struct rb_node *left;

	struct rb_root_cached rb;

	unsigned count;

	u64 min_vdisktime;

	struct cfq_ttime ttime;

};

#define CFQ_RB_ROOT	(struct cfq_rb_root) { .rb = RB_ROOT, \

#define CFQ_RB_ROOT	(struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \

			.ttime = {.last_end_request = ktime_get_ns(),},}



/*
@@ -981,10 +980,9 @@ static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) 


static void update_min_vdisktime(struct cfq_rb_root *st)

{

	struct cfq_group *cfqg;

	if (!RB_EMPTY_ROOT(&st->rb.rb_root)) {

		struct cfq_group *cfqg = rb_entry_cfqg(st->rb.rb_leftmost);



	if (st->left) {

		cfqg = rb_entry_cfqg(st->left);

		st->min_vdisktime = max_vdisktime(st->min_vdisktime,

						  cfqg->vdisktime);

	}
@@ -1166,46 +1164,25 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, 
	}

}



/*

 * The below is leftmost cache rbtree addon

 */

static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)

{

	/* Service tree is empty */

	if (!root->count)

		return NULL;



	if (!root->left)

		root->left = rb_first(&root->rb);



	if (root->left)

		return rb_entry(root->left, struct cfq_queue, rb_node);



	return NULL;

	return rb_entry(rb_first_cached(&root->rb), struct cfq_queue, rb_node);

}



static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)

{

	if (!root->left)

		root->left = rb_first(&root->rb);



	if (root->left)

		return rb_entry_cfqg(root->left);



	return NULL;

	return rb_entry_cfqg(rb_first_cached(&root->rb));

}



static void rb_erase_init(struct rb_node *n, struct rb_root *root)

static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)

{

	rb_erase(n, root);

	rb_erase_cached(n, &root->rb);

	RB_CLEAR_NODE(n);

}



static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)

{

	if (root->left == n)

		root->left = NULL;

	rb_erase_init(n, &root->rb);

	--root->count;

}
@@ -1255,11 +1232,11 @@ cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) 
static void

__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)

{

	struct rb_node **node = &st->rb.rb_node;

	struct rb_node **node = &st->rb.rb_root.rb_node;

	struct rb_node *parent = NULL;

	struct cfq_group *__cfqg;

	s64 key = cfqg_key(st, cfqg);

	int left = 1;

	bool leftmost = true;



	while (*node != NULL) {

		parent = *node;
@@ -1269,15 +1246,12 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) 
			node = &parent->rb_left;

		else {

			node = &parent->rb_right;

			left = 0;

			leftmost = false;

		}

	}



	if (left)

		st->left = &cfqg->rb_node;



	rb_link_node(&cfqg->rb_node, parent, node);

	rb_insert_color(&cfqg->rb_node, &st->rb);

	rb_insert_color_cached(&cfqg->rb_node, &st->rb, leftmost);

}



/*
@@ -1378,7 +1352,7 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) 
	 * so that groups get lesser vtime based on their weights, so that

	 * if group does not loose all if it was not continuously backlogged.

	 */

	n = rb_last(&st->rb);

	n = rb_last(&st->rb.rb_root);

	if (n) {

		__cfqg = rb_entry_cfqg(n);

		cfqg->vdisktime = __cfqg->vdisktime +
@@ -2220,14 +2194,14 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
	struct cfq_queue *__cfqq;

	u64 rb_key;

	struct cfq_rb_root *st;

	int left;

	bool leftmost = true;

	int new_cfqq = 1;

	u64 now = ktime_get_ns();



	st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));

	if (cfq_class_idle(cfqq)) {

		rb_key = CFQ_IDLE_DELAY;

		parent = rb_last(&st->rb);

		parent = rb_last(&st->rb.rb_root);

		if (parent && parent != &cfqq->rb_node) {

			__cfqq = rb_entry(parent, struct cfq_queue, rb_node);

			rb_key += __cfqq->rb_key;
@@ -2261,10 +2235,9 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
		cfqq->service_tree = NULL;

	}



	left = 1;

	parent = NULL;

	cfqq->service_tree = st;

	p = &st->rb.rb_node;

	p = &st->rb.rb_root.rb_node;

	while (*p) {

		parent = *p;

		__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
@@ -2276,16 +2249,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
			p = &parent->rb_left;

		else {

			p = &parent->rb_right;

			left = 0;

			leftmost = false;

		}

	}



	if (left)

		st->left = &cfqq->rb_node;



	cfqq->rb_key = rb_key;

	rb_link_node(&cfqq->rb_node, parent, p);

	rb_insert_color(&cfqq->rb_node, &st->rb);

	rb_insert_color_cached(&cfqq->rb_node, &st->rb, leftmost);

	st->count++;

	if (add_front || !new_cfqq)

		return;
@@ -2732,7 +2702,7 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 
	/* There is nothing to dispatch */

	if (!st)

		return NULL;

	if (RB_EMPTY_ROOT(&st->rb))

	if (RB_EMPTY_ROOT(&st->rb.rb_root))

		return NULL;

	return cfq_rb_first(st);

}
@@ -3219,7 +3189,7 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) 
	struct cfq_rb_root *st = &cfqd->grp_service_tree;

	struct cfq_group *cfqg;



	if (RB_EMPTY_ROOT(&st->rb))

	if (RB_EMPTY_ROOT(&st->rb.rb_root))

		return NULL;

	cfqg = cfq_rb_first_group(st);

	update_min_vdisktime(st);