cfq-iosched: sort IDLE queues into the rbtree

Same treatment as the RT conversion, just put the sorted idle
branch at the end of the tree.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 81c057e..6a6a5f7 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -92,7 +92,6 @@ struct cfq_data {
         */
        struct cfq_rb_root service_tree;
        struct list_head cur_rr;
-       struct list_head idle_rr;
        unsigned int busy_queues;
 
        /*
@@ -467,25 +466,33 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
 
        while (*p) {
                struct cfq_queue *__cfqq;
+               struct rb_node **n;
 
                parent = *p;
                __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
 
                /*
                 * sort RT queues first, we always want to give
-                * preference to them. after that, sort on the next
-                * service time.
+                * preference to them. IDLE queues goes to the back.
+                * after that, sort on the next service time.
                 */
                if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
-                       p = &(*p)->rb_left;
+                       n = &(*p)->rb_left;
                else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
-                       p = &(*p)->rb_right;
+                       n = &(*p)->rb_right;
+               else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
+                       n = &(*p)->rb_left;
+               else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
+                       n = &(*p)->rb_right;
                else if (rb_key < __cfqq->rb_key)
-                       p = &(*p)->rb_left;
-               else {
-                       p = &(*p)->rb_right;
+                       n = &(*p)->rb_left;
+               else
+                       n = &(*p)->rb_right;
+
+               if (n == &(*p)->rb_right)
                        left = 0;
-               }
+
+               p = n;
        }
 
        if (left)
@@ -506,19 +513,7 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
        if (!cfq_cfqq_on_rr(cfqq))
                return;
 
-       list_del_init(&cfqq->cfq_list);
-
-       if (cfq_class_idle(cfqq)) {
-               /*
-                * IDLE goes to the tail of the idle list
-                */
-               list_add_tail(&cfqq->cfq_list, &cfqd->idle_rr);
-       } else {
-               /*
-                * RT and BE queues, sort into the rbtree
-                */
-               cfq_service_tree_add(cfqd, cfqq);
-       }
+       cfq_service_tree_add(cfqd, cfqq);
 }
 
 /*
@@ -797,20 +792,22 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
                cfqq = list_entry_cfqq(cfqd->cur_rr.next);
        } else if (!RB_EMPTY_ROOT(&cfqd->service_tree.rb)) {
                struct rb_node *n = cfq_rb_first(&cfqd->service_tree);
+               unsigned long end;
 
                cfqq = rb_entry(n, struct cfq_queue, rb_node);
-       } else if (!list_empty(&cfqd->idle_rr)) {
-               /*
-                * if we have idle queues and no rt or be queues had pending
-                * requests, either allow immediate service if the grace period
-                * has passed or arm the idle grace timer
-                */
-               unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
-
-               if (time_after_eq(jiffies, end))
-                       cfqq = list_entry_cfqq(cfqd->idle_rr.next);
-               else
-                       mod_timer(&cfqd->idle_class_timer, end);
+               if (cfq_class_idle(cfqq)) {
+                       /*
+                        * if we have idle queues and no rt or be queues had
+                        * pending requests, either allow immediate service if
+                        * the grace period has passed or arm the idle grace
+                        * timer
+                        */
+                       end = cfqd->last_end_request + CFQ_IDLE_GRACE;
+                       if (time_before(jiffies, end)) {
+                               mod_timer(&cfqd->idle_class_timer, end);
+                               cfqq = NULL;
+                       }
+               }
        }
 
        return cfqq;
@@ -1074,7 +1071,6 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
        }
 
        dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
-       dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
 
        cfq_slice_expired(cfqd, 0, 0);
 
@@ -2047,7 +2043,6 @@ static void *cfq_init_queue(request_queue_t *q)
 
        cfqd->service_tree = CFQ_RB_ROOT;
        INIT_LIST_HEAD(&cfqd->cur_rr);
-       INIT_LIST_HEAD(&cfqd->idle_rr);
        INIT_LIST_HEAD(&cfqd->cic_list);
 
        cfqd->cfq_hash = kmalloc_node(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL, q->node);