Re: [PATCH 1/8 v2] cfq-iosched: Introduce cfq_entity for CFQ queue

[Vivek Goyal <vgoyal@redhat.com>]

On Mon, Dec 13, 2010 at 09:44:24AM +0800, Gui Jianfeng wrote:
> Introduce cfq_entity for CFQ queue
> 
> Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
> ---
>  block/cfq-iosched.c |  125 +++++++++++++++++++++++++++++++++-----------------
>  1 files changed, 82 insertions(+), 43 deletions(-)
> 
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 5d0349d..9b07a24 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -91,20 +91,31 @@ struct cfq_rb_root {
>  #define CFQ_RB_ROOT	(struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
>  			.count = 0, .min_vdisktime = 0, }
>  
> +
> +/*
> + * This's the CFQ queue schedule entity which is scheduled on  service tree.
> + */
> +struct cfq_entity {
> +	/* service tree */
> +	struct cfq_rb_root *service_tree;
> +	/* service_tree member */
> +	struct rb_node rb_node;
> +	/* service_tree key, represent the position on the tree */
> +	unsigned long rb_key;
> +};
> +
>  /*
>   * Per process-grouping structure
>   */
>  struct cfq_queue {
> +	/* The schedule entity */
> +	struct cfq_entity cfqe;
>  	/* reference count */
>  	atomic_t ref;
>  	/* various state flags, see below */
>  	unsigned int flags;
>  	/* parent cfq_data */
>  	struct cfq_data *cfqd;
> -	/* service_tree member */
> -	struct rb_node rb_node;
> -	/* service_tree key */
> -	unsigned long rb_key;
>  	/* prio tree member */
>  	struct rb_node p_node;
>  	/* prio tree root we belong to, if any */
> @@ -143,7 +154,6 @@ struct cfq_queue {
>  	u32 seek_history;
>  	sector_t last_request_pos;
>  
> -	struct cfq_rb_root *service_tree;
>  	struct cfq_queue *new_cfqq;
>  	struct cfq_group *cfqg;
>  	struct cfq_group *orig_cfqg;
> @@ -302,6 +312,15 @@ struct cfq_data {
>  	struct rcu_head rcu;
>  };
>  
> +static inline struct cfq_queue *
> +cfqq_of_entity(struct cfq_entity *cfqe)
> +{
> +	if (cfqe)
> +		return container_of(cfqe, struct cfq_queue,
> +				    cfqe);
> +	return NULL;
> +}
> +
>  static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
>  
>  static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
> @@ -743,7 +762,7 @@ 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)
> +static struct cfq_entity *cfq_rb_first(struct cfq_rb_root *root)
>  {
>  	/* Service tree is empty */
>  	if (!root->count)
> @@ -753,7 +772,7 @@ static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
>  		root->left = rb_first(&root->rb);
>  
>  	if (root->left)
> -		return rb_entry(root->left, struct cfq_queue, rb_node);
> +		return rb_entry(root->left, struct cfq_entity, rb_node);
>  
>  	return NULL;
>  }
> @@ -1170,21 +1189,24 @@ static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
>  static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  				 bool add_front)
>  {
> +	struct cfq_entity *cfqe;
>  	struct rb_node **p, *parent;
> -	struct cfq_queue *__cfqq;
> +	struct cfq_entity *__cfqe;
>  	unsigned long rb_key;
>  	struct cfq_rb_root *service_tree;
>  	int left;
>  	int new_cfqq = 1;
>  	int group_changed = 0;
>  
> +	cfqe = &cfqq->cfqe;
> +
>  #ifdef CONFIG_CFQ_GROUP_IOSCHED
>  	if (!cfqd->cfq_group_isolation
>  	    && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
>  	    && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
>  		/* Move this cfq to root group */
>  		cfq_log_cfqq(cfqd, cfqq, "moving to root group");
> -		if (!RB_EMPTY_NODE(&cfqq->rb_node))
> +		if (!RB_EMPTY_NODE(&cfqe->rb_node))
>  			cfq_group_service_tree_del(cfqd, cfqq->cfqg);
>  		cfqq->orig_cfqg = cfqq->cfqg;
>  		cfqq->cfqg = &cfqd->root_group;
> @@ -1194,7 +1216,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  		   && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
>  		/* cfqq is sequential now needs to go to its original group */
>  		BUG_ON(cfqq->cfqg != &cfqd->root_group);
> -		if (!RB_EMPTY_NODE(&cfqq->rb_node))
> +		if (!RB_EMPTY_NODE(&cfqe->rb_node))
>  			cfq_group_service_tree_del(cfqd, cfqq->cfqg);
>  		cfq_put_cfqg(cfqq->cfqg);
>  		cfqq->cfqg = cfqq->orig_cfqg;
> @@ -1209,9 +1231,11 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  	if (cfq_class_idle(cfqq)) {
>  		rb_key = CFQ_IDLE_DELAY;
>  		parent = rb_last(&service_tree->rb);
> -		if (parent && parent != &cfqq->rb_node) {
> -			__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
> -			rb_key += __cfqq->rb_key;
> +		if (parent && parent != &cfqe->rb_node) {
> +			__cfqe = rb_entry(parent,
> +						  struct cfq_entity,
> +						  rb_node);

Above can fit into a single line or at max two lines?

> +			rb_key += __cfqe->rb_key;
>  		} else
>  			rb_key += jiffies;
>  	} else if (!add_front) {
> @@ -1226,37 +1250,39 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  		cfqq->slice_resid = 0;
>  	} else {
>  		rb_key = -HZ;
> -		__cfqq = cfq_rb_first(service_tree);
> -		rb_key += __cfqq ? __cfqq->rb_key : jiffies;
> +		__cfqe = cfq_rb_first(service_tree);
> +		rb_key += __cfqe ? __cfqe->rb_key : jiffies;
>  	}
>  
> -	if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
> +	if (!RB_EMPTY_NODE(&cfqe->rb_node)) {
>  		new_cfqq = 0;
>  		/*
>  		 * same position, nothing more to do
>  		 */
> -		if (rb_key == cfqq->rb_key &&
> -		    cfqq->service_tree == service_tree)
> +		if (rb_key == cfqe->rb_key &&
> +		    cfqe->service_tree == service_tree)
>  			return;
>  
> -		cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
> -		cfqq->service_tree = NULL;
> +		cfq_rb_erase(&cfqe->rb_node,
> +			     cfqe->service_tree);

Above can fit on single line?

> +		cfqe->service_tree = NULL;
>  	}
>  
>  	left = 1;
>  	parent = NULL;
> -	cfqq->service_tree = service_tree;
> +	cfqe->service_tree = service_tree;
>  	p = &service_tree->rb.rb_node;
>  	while (*p) {
>  		struct rb_node **n;
>  
>  		parent = *p;
> -		__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
> +		__cfqe = rb_entry(parent, struct cfq_entity,
> +					  rb_node);

Single line.

>  
>  		/*
>  		 * sort by key, that represents service time.
>  		 */
> -		if (time_before(rb_key, __cfqq->rb_key))
> +		if (time_before(rb_key, __cfqe->rb_key))
>  			n = &(*p)->rb_left;
>  		else {
>  			n = &(*p)->rb_right;
> @@ -1267,11 +1293,11 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  	}
>  
>  	if (left)
> -		service_tree->left = &cfqq->rb_node;
> +		service_tree->left = &cfqe->rb_node;
>  
> -	cfqq->rb_key = rb_key;
> -	rb_link_node(&cfqq->rb_node, parent, p);
> -	rb_insert_color(&cfqq->rb_node, &service_tree->rb);
> +	cfqe->rb_key = rb_key;
> +	rb_link_node(&cfqe->rb_node, parent, p);
> +	rb_insert_color(&cfqe->rb_node, &service_tree->rb);
>  	service_tree->count++;
>  	if ((add_front || !new_cfqq) && !group_changed)
>  		return;
> @@ -1373,13 +1399,17 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>   */
>  static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>  {
> +	struct cfq_entity *cfqe;
>  	cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
>  	BUG_ON(!cfq_cfqq_on_rr(cfqq));
>  	cfq_clear_cfqq_on_rr(cfqq);
>  
> -	if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
> -		cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
> -		cfqq->service_tree = NULL;
> +	cfqe = &cfqq->cfqe;
> +
> +	if (!RB_EMPTY_NODE(&cfqe->rb_node)) {
> +		cfq_rb_erase(&cfqe->rb_node,
> +			     cfqe->service_tree);

Single line above.


> +		cfqe->service_tree = NULL;
>  	}
>  	if (cfqq->p_root) {
>  		rb_erase(&cfqq->p_node, cfqq->p_root);
> @@ -1707,13 +1737,13 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
>  		return NULL;
>  	if (RB_EMPTY_ROOT(&service_tree->rb))
>  		return NULL;
> -	return cfq_rb_first(service_tree);
> +	return cfqq_of_entity(cfq_rb_first(service_tree));
>  }
>  
>  static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
>  {
>  	struct cfq_group *cfqg;
> -	struct cfq_queue *cfqq;
> +	struct cfq_entity *cfqe;
>  	int i, j;
>  	struct cfq_rb_root *st;
>  
> @@ -1724,9 +1754,11 @@ static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
>  	if (!cfqg)
>  		return NULL;
>  
> -	for_each_cfqg_st(cfqg, i, j, st)
> -		if ((cfqq = cfq_rb_first(st)) != NULL)
> -			return cfqq;
> +	for_each_cfqg_st(cfqg, i, j, st) {
> +		cfqe = cfq_rb_first(st);
> +		if (cfqe != NULL)
> +			return cfqq_of_entity(cfqe);
> +	}
>  	return NULL;
>  }
>  
> @@ -1863,9 +1895,12 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
>  
>  static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>  {
> +	struct cfq_entity *cfqe;
>  	enum wl_prio_t prio = cfqq_prio(cfqq);
> -	struct cfq_rb_root *service_tree = cfqq->service_tree;
> +	struct cfq_rb_root *service_tree;
>  
> +	cfqe = &cfqq->cfqe;
> +	service_tree = cfqe->service_tree;
>  	BUG_ON(!service_tree);
>  	BUG_ON(!service_tree->count);
>  
> @@ -2075,7 +2110,7 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
>  static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
>  				struct cfq_group *cfqg, enum wl_prio_t prio)
>  {
> -	struct cfq_queue *queue;
> +	struct cfq_entity *cfqe;
>  	int i;
>  	bool key_valid = false;
>  	unsigned long lowest_key = 0;
> @@ -2083,10 +2118,11 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
>  
>  	for (i = 0; i <= SYNC_WORKLOAD; ++i) {
>  		/* select the one with lowest rb_key */
> -		queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
> -		if (queue &&
> -		    (!key_valid || time_before(queue->rb_key, lowest_key))) {
> -			lowest_key = queue->rb_key;
> +		cfqe = cfq_rb_first(service_tree_for(cfqg, prio, i));
> +		if (cfqe &&
> +		    (!key_valid ||
> +		     time_before(cfqe->rb_key, lowest_key))) {

Merge two lines into one above.

> +			lowest_key = cfqe->rb_key;
>  			cur_best = i;
>  			key_valid = true;
>  		}
> @@ -2834,7 +2870,10 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)
>  static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>  			  pid_t pid, bool is_sync)
>  {
> -	RB_CLEAR_NODE(&cfqq->rb_node);
> +	struct cfq_entity *cfqe;
> +
> +	cfqe = &cfqq->cfqe;
> +	RB_CLEAR_NODE(&cfqe->rb_node);
>  	RB_CLEAR_NODE(&cfqq->p_node);
>  	INIT_LIST_HEAD(&cfqq->fifo);
>  
> @@ -3243,7 +3282,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
>  	/* Allow preemption only if we are idling on sync-noidle tree */
>  	if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
>  	    cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
> -	    new_cfqq->service_tree->count == 2 &&
> +	    new_cfqq->cfqe.service_tree->count == 2 &&
>  	    RB_EMPTY_ROOT(&cfqq->sort_list))
>  		return true;
>  

Apart from above minor nits, this patch looks good to me.

Acked-by: Vivek Goyal <vgoyal@redhat.com>

Vivek