1 files changed, 198 insertions, 25 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 090a4ee75b9d..0d3b70de3d80 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -80,6 +80,14 @@ struct cfq_data {
          * rr list of queues with requests and the count of them
          */
         struct cfq_rb_root service_tree;
+
+        /*
+         * Each priority tree is sorted by next_request position.  These
+         * trees are used when determining if two or more queues are
+         * interleaving requests (see cfq_close_cooperator).
+         */
+        struct rb_root prio_trees[CFQ_PRIO_LISTS];
+
         unsigned int busy_queues;
         /*
          * Used to track any pending rt requests so we can pre-empt current
@@ -144,6 +152,8 @@ struct cfq_queue {
         struct rb_node rb_node;
         /* service_tree key */
         unsigned long rb_key;
+        /* prio tree member */
+        struct rb_node p_node;
         /* sorted list of pending requests */
         struct rb_root sort_list;
         /* if fifo isn't expired, next request to serve */
@@ -182,6 +192,7 @@ enum cfqq_state_flags {
         CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
         CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
         CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
+        CFQ_CFQQ_FLAG_coop,             /* has done a coop jump of the queue */
 };
 
 #define CFQ_CFQQ_FNS(name)                                              \
@@ -208,6 +219,7 @@ CFQ_CFQQ_FNS(idle_window);
 CFQ_CFQQ_FNS(prio_changed);
 CFQ_CFQQ_FNS(slice_new);
 CFQ_CFQQ_FNS(sync);
+CFQ_CFQQ_FNS(coop);
 #undef CFQ_CFQQ_FNS
 
 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
@@ -416,13 +428,17 @@ static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
         return NULL;
 }
 
+static void rb_erase_init(struct rb_node *n, struct rb_root *root)
+{
+        rb_erase(n, root);
+        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(n, &root->rb);
-        RB_CLEAR_NODE(n);
+        rb_erase_init(n, &root->rb);
 }
 
 /*
@@ -467,8 +483,8 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
  * requests waiting to be processed. It is sorted in the order that
  * we will service the queues.
  */
-static void cfq_service_tree_add(struct cfq_data *cfqd,
-                                    struct cfq_queue *cfqq, int add_front)
+static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+                                 int add_front)
 {
         struct rb_node **p, *parent;
         struct cfq_queue *__cfqq;
@@ -541,6 +557,63 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
         rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
 }
 
+static struct cfq_queue *
+cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
+                     struct rb_node **ret_parent, struct rb_node ***rb_link)
+{
+        struct rb_root *root = &cfqd->prio_trees[ioprio];
+        struct rb_node **p, *parent;
+        struct cfq_queue *cfqq = NULL;
+
+        parent = NULL;
+        p = &root->rb_node;
+        while (*p) {
+                struct rb_node **n;
+
+                parent = *p;
+                cfqq = rb_entry(parent, struct cfq_queue, p_node);
+
+                /*
+                 * Sort strictly based on sector.  Smallest to the left,
+                 * largest to the right.
+                 */
+                if (sector > cfqq->next_rq->sector)
+                        n = &(*p)->rb_right;
+                else if (sector < cfqq->next_rq->sector)
+                        n = &(*p)->rb_left;
+                else
+                        break;
+                p = n;
+        }
+
+        *ret_parent = parent;
+        if (rb_link)
+                *rb_link = p;
+        return NULL;
+}
+
+static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+        struct rb_root *root = &cfqd->prio_trees[cfqq->ioprio];
+        struct rb_node **p, *parent;
+        struct cfq_queue *__cfqq;
+
+        if (!RB_EMPTY_NODE(&cfqq->p_node))
+                rb_erase_init(&cfqq->p_node, root);
+
+        if (cfq_class_idle(cfqq))
+                return;
+        if (!cfqq->next_rq)
+                return;
+
+        __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->ioprio, cfqq->next_rq->sector,
+                                         &parent, &p);
+        BUG_ON(__cfqq);
+
+        rb_link_node(&cfqq->p_node, parent, p);
+        rb_insert_color(&cfqq->p_node, root);
+}
+
 /*
  * Update cfqq's position in the service tree.
  */
@@ -549,8 +622,10 @@ static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         /*
          * Resorting requires the cfqq to be on the RR list already.
          */
-        if (cfq_cfqq_on_rr(cfqq))
+        if (cfq_cfqq_on_rr(cfqq)) {
                 cfq_service_tree_add(cfqd, cfqq, 0);
+                cfq_prio_tree_add(cfqd, cfqq);
+        }
 }
 
 /*
@@ -581,6 +656,8 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
         if (!RB_EMPTY_NODE(&cfqq->rb_node))
                 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
+        if (!RB_EMPTY_NODE(&cfqq->p_node))
+                rb_erase_init(&cfqq->p_node, &cfqd->prio_trees[cfqq->ioprio]);
 
         BUG_ON(!cfqd->busy_queues);
         cfqd->busy_queues--;
@@ -610,7 +687,7 @@ static void cfq_add_rq_rb(struct request *rq)
 {
         struct cfq_queue *cfqq = RQ_CFQQ(rq);
         struct cfq_data *cfqd = cfqq->cfqd;
-        struct request *__alias;
+        struct request *__alias, *prev;
 
         cfqq->queued[rq_is_sync(rq)]++;
 
@@ -627,7 +704,15 @@ static void cfq_add_rq_rb(struct request *rq)
         /*
          * check if this request is a better next-serve candidate
          */
+        prev = cfqq->next_rq;
         cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
+
+        /*
+         * adjust priority tree position, if ->next_rq changes
+         */
+        if (prev != cfqq->next_rq)
+                cfq_prio_tree_add(cfqd, cfqq);
+
         BUG_ON(!cfqq->next_rq);
 }
 
@@ -840,11 +925,15 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
 /*
  * Get and set a new active queue for service.
  */
-static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
+static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
+                                              struct cfq_queue *cfqq)
 {
-        struct cfq_queue *cfqq;
+        if (!cfqq) {
+                cfqq = cfq_get_next_queue(cfqd);
+                if (cfqq)
+                        cfq_clear_cfqq_coop(cfqq);
+        }
 
-        cfqq = cfq_get_next_queue(cfqd);
         __cfq_set_active_queue(cfqd, cfqq);
         return cfqq;
 }
@@ -868,17 +957,89 @@ static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
         return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean;
 }
 
-static int cfq_close_cooperator(struct cfq_data *cfq_data,
-                                struct cfq_queue *cfqq)
+static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
+                                    struct cfq_queue *cur_cfqq)
+{
+        struct rb_root *root = &cfqd->prio_trees[cur_cfqq->ioprio];
+        struct rb_node *parent, *node;
+        struct cfq_queue *__cfqq;
+        sector_t sector = cfqd->last_position;
+
+        if (RB_EMPTY_ROOT(root))
+                return NULL;
+
+        /*
+         * First, if we find a request starting at the end of the last
+         * request, choose it.
+         */
+        __cfqq = cfq_prio_tree_lookup(cfqd, cur_cfqq->ioprio,
+                                      sector, &parent, NULL);
+        if (__cfqq)
+                return __cfqq;
+
+        /*
+         * If the exact sector wasn't found, the parent of the NULL leaf
+         * will contain the closest sector.
+         */
+        __cfqq = rb_entry(parent, struct cfq_queue, p_node);
+        if (cfq_rq_close(cfqd, __cfqq->next_rq))
+                return __cfqq;
+
+        if (__cfqq->next_rq->sector < sector)
+                node = rb_next(&__cfqq->p_node);
+        else
+                node = rb_prev(&__cfqq->p_node);
+        if (!node)
+                return NULL;
+
+        __cfqq = rb_entry(node, struct cfq_queue, p_node);
+        if (cfq_rq_close(cfqd, __cfqq->next_rq))
+                return __cfqq;
+
+        return NULL;
+}
+
+/*
+ * cfqd - obvious
+ * cur_cfqq - passed in so that we don't decide that the current queue is
+ *            closely cooperating with itself.
+ *
+ * So, basically we're assuming that that cur_cfqq has dispatched at least
+ * one request, and that cfqd->last_position reflects a position on the disk
+ * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
+ * assumption.
+ */
+static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
+                                              struct cfq_queue *cur_cfqq,
+                                              int probe)
 {
+        struct cfq_queue *cfqq;
+
+        /*
+         * A valid cfq_io_context is necessary to compare requests against
+         * the seek_mean of the current cfqq.
+         */
+        if (!cfqd->active_cic)
+                return NULL;
+
         /*
          * We should notice if some of the queues are cooperating, eg
          * working closely on the same area of the disk. In that case,
          * we can group them together and don't waste time idling.
          */
-        return 0;
+        cfqq = cfqq_close(cfqd, cur_cfqq);
+        if (!cfqq)
+                return NULL;
+
+        if (cfq_cfqq_coop(cfqq))
+                return NULL;
+
+        if (!probe)
+                cfq_mark_cfqq_coop(cfqq);
+        return cfqq;
 }
 
+
 #define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024))
 
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
@@ -917,13 +1078,6 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
         if (!cic || !atomic_read(&cic->ioc->nr_tasks))
                 return;
 
-        /*
-         * See if this prio level has a good candidate
-         */
-        if (cfq_close_cooperator(cfqd, cfqq) &&
-            (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2))
-                return;
-
         cfq_mark_cfqq_wait_request(cfqq);
 
         /*
@@ -1000,7 +1154,7 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
  */
 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 {
-        struct cfq_queue *cfqq;
+        struct cfq_queue *cfqq, *new_cfqq = NULL;
 
         cfqq = cfqd->active_queue;
         if (!cfqq)
@@ -1034,6 +1188,16 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
                 goto keep_queue;
 
         /*
+         * If another queue has a request waiting within our mean seek
+         * distance, let it run.  The expire code will check for close
+         * cooperators and put the close queue at the front of the service
+         * tree.
+         */
+        new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
+        if (new_cfqq)
+                goto expire;
+
+        /*
          * No requests pending. If the active queue still has requests in
          * flight or is idling for a new request, allow either of these
          * conditions to happen (or time out) before selecting a new queue.
@@ -1047,7 +1211,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 expire:
         cfq_slice_expired(cfqd, 0);
 new_queue:
-        cfqq = cfq_set_active_queue(cfqd);
+        cfqq = cfq_set_active_queue(cfqd, new_cfqq);
 keep_queue:
         return cfqq;
 }
@@ -1508,6 +1672,7 @@ retry:
                 }
 
                 RB_CLEAR_NODE(&cfqq->rb_node);
+                RB_CLEAR_NODE(&cfqq->p_node);
                 INIT_LIST_HEAD(&cfqq->fifo);
 
                 atomic_set(&cfqq->ref, 0);
@@ -2000,16 +2165,24 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
          * or if we want to idle in case it has no pending requests.
          */
         if (cfqd->active_queue == cfqq) {
+                const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
+
                 if (cfq_cfqq_slice_new(cfqq)) {
                         cfq_set_prio_slice(cfqd, cfqq);
                         cfq_clear_cfqq_slice_new(cfqq);
                 }
+                /*
+                 * If there are no requests waiting in this queue, and
+                 * there are other queues ready to issue requests, AND
+                 * those other queues are issuing requests within our
+                 * mean seek distance, give them a chance to run instead
+                 * of idling.
+                 */
                 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
                         cfq_slice_expired(cfqd, 1);
-                else if (sync && !rq_noidle(rq) &&
-                         RB_EMPTY_ROOT(&cfqq->sort_list)) {
+                else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
+                         sync && !rq_noidle(rq))
                         cfq_arm_slice_timer(cfqd);
-                }
         }
 
         if (!cfqd->rq_in_driver)