Merge branch 'cfq-2.6.33' into for-2.6.33
[linux-2.6.git] / block / cfq-iosched.c
index 757010d..8b5ba18 100644 (file)
@@ -27,6 +27,8 @@ static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
 static const int cfq_slice_async_rq = 2;
 static int cfq_slice_idle = HZ / 125;
+static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
+static const int cfq_hist_divisor = 4;
 
 /*
  * offset from end of service tree
@@ -73,8 +75,9 @@ static DEFINE_SPINLOCK(ioc_gone_lock);
 struct cfq_rb_root {
        struct rb_root rb;
        struct rb_node *left;
+       unsigned count;
 };
-#define CFQ_RB_ROOT    (struct cfq_rb_root) { RB_ROOT, NULL, }
+#define CFQ_RB_ROOT    (struct cfq_rb_root) { RB_ROOT, NULL, 0, }
 
 /*
  * Per process-grouping structure
@@ -126,19 +129,48 @@ struct cfq_queue {
 
        pid_t pid;
 
+       struct cfq_rb_root *service_tree;
        struct cfq_queue *new_cfqq;
 };
 
 /*
+ * First index in the service_trees.
+ * IDLE is handled separately, so it has negative index
+ */
+enum wl_prio_t {
+       IDLE_WORKLOAD = -1,
+       BE_WORKLOAD = 0,
+       RT_WORKLOAD = 1
+};
+
+/*
+ * Second index in the service_trees.
+ */
+enum wl_type_t {
+       ASYNC_WORKLOAD = 0,
+       SYNC_NOIDLE_WORKLOAD = 1,
+       SYNC_WORKLOAD = 2
+};
+
+
+/*
  * Per block device queue structure
  */
 struct cfq_data {
        struct request_queue *queue;
 
        /*
-        * rr list of queues with requests and the count of them
+        * rr lists of queues with requests, onle rr for each priority class.
+        * Counts are embedded in the cfq_rb_root
+        */
+       struct cfq_rb_root service_trees[2][3];
+       struct cfq_rb_root service_tree_idle;
+       /*
+        * The priority currently being served
         */
-       struct cfq_rb_root service_tree;
+       enum wl_prio_t serving_prio;
+       enum wl_type_t serving_type;
+       unsigned long workload_expires;
 
        /*
         * Each priority tree is sorted by next_request position.  These
@@ -148,6 +180,7 @@ struct cfq_data {
        struct rb_root prio_trees[CFQ_PRIO_LISTS];
 
        unsigned int busy_queues;
+       unsigned int busy_queues_avg[2];
 
        int rq_in_driver[2];
        int sync_flight;
@@ -199,6 +232,16 @@ struct cfq_data {
        unsigned long last_end_sync_rq;
 };
 
+static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio,
+                                           enum wl_type_t type,
+                                           struct cfq_data *cfqd)
+{
+       if (prio == IDLE_WORKLOAD)
+               return &cfqd->service_tree_idle;
+
+       return &cfqd->service_trees[prio][type];
+}
+
 enum cfqq_state_flags {
        CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
        CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
@@ -243,6 +286,35 @@ CFQ_CFQQ_FNS(coop);
 #define cfq_log(cfqd, fmt, args...)    \
        blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
 
+static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
+{
+       if (cfq_class_idle(cfqq))
+               return IDLE_WORKLOAD;
+       if (cfq_class_rt(cfqq))
+               return RT_WORKLOAD;
+       return BE_WORKLOAD;
+}
+
+
+static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
+{
+       if (!cfq_cfqq_sync(cfqq))
+               return ASYNC_WORKLOAD;
+       if (!cfq_cfqq_idle_window(cfqq))
+               return SYNC_NOIDLE_WORKLOAD;
+       return SYNC_WORKLOAD;
+}
+
+static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
+{
+       if (wl == IDLE_WORKLOAD)
+               return cfqd->service_tree_idle.count;
+
+       return cfqd->service_trees[wl][ASYNC_WORKLOAD].count
+               + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
+               + cfqd->service_trees[wl][SYNC_WORKLOAD].count;
+}
+
 static void cfq_dispatch_insert(struct request_queue *, struct request *);
 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
                                       struct io_context *, gfp_t);
@@ -315,10 +387,49 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
 }
 
+/*
+ * get averaged number of queues of RT/BE priority.
+ * average is updated, with a formula that gives more weight to higher numbers,
+ * to quickly follows sudden increases and decrease slowly
+ */
+
+static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt)
+{
+       unsigned min_q, max_q;
+       unsigned mult  = cfq_hist_divisor - 1;
+       unsigned round = cfq_hist_divisor / 2;
+       unsigned busy = cfq_busy_queues_wl(rt, cfqd);
+
+       min_q = min(cfqd->busy_queues_avg[rt], busy);
+       max_q = max(cfqd->busy_queues_avg[rt], busy);
+       cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
+               cfq_hist_divisor;
+       return cfqd->busy_queues_avg[rt];
+}
+
 static inline void
 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-       cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
+       unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
+       if (cfqd->cfq_latency) {
+               /* interested queues (we consider only the ones with the same
+                * priority class) */
+               unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq));
+               unsigned sync_slice = cfqd->cfq_slice[1];
+               unsigned expect_latency = sync_slice * iq;
+               if (expect_latency > cfq_target_latency) {
+                       unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
+                       /* scale low_slice according to IO priority
+                        * and sync vs async */
+                       unsigned low_slice =
+                               min(slice, base_low_slice * slice / sync_slice);
+                       /* the adapted slice value is scaled to fit all iqs
+                        * into the target latency */
+                       slice = max(slice * cfq_target_latency / expect_latency,
+                                   low_slice);
+               }
+       }
+       cfqq->slice_end = jiffies + slice;
        cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
 }
 
@@ -457,6 +568,7 @@ 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;
 }
 
 /*
@@ -497,7 +609,7 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
 }
 
 /*
- * The cfqd->service_tree holds all pending cfq_queue's that have
+ * The cfqd->service_trees holds all pending cfq_queue's that have
  * requests waiting to be processed. It is sorted in the order that
  * we will service the queues.
  */
@@ -507,11 +619,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        struct rb_node **p, *parent;
        struct cfq_queue *__cfqq;
        unsigned long rb_key;
+       struct cfq_rb_root *service_tree;
        int left;
 
+       service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd);
        if (cfq_class_idle(cfqq)) {
                rb_key = CFQ_IDLE_DELAY;
-               parent = rb_last(&cfqd->service_tree.rb);
+               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;
@@ -529,7 +643,7 @@ 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(&cfqd->service_tree);
+               __cfqq = cfq_rb_first(service_tree);
                rb_key += __cfqq ? __cfqq->rb_key : jiffies;
        }
 
@@ -537,15 +651,18 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                /*
                 * same position, nothing more to do
                 */
-               if (rb_key == cfqq->rb_key)
+               if (rb_key == cfqq->rb_key &&
+                   cfqq->service_tree == service_tree)
                        return;
 
-               cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
+               cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+               cfqq->service_tree = NULL;
        }
 
        left = 1;
        parent = NULL;
-       p = &cfqd->service_tree.rb.rb_node;
+       cfqq->service_tree = service_tree;
+       p = &service_tree->rb.rb_node;
        while (*p) {
                struct rb_node **n;
 
@@ -553,35 +670,25 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
 
                /*
-                * sort RT queues first, we always want to give
-                * preference to them. IDLE queues goes to the back.
-                * after that, sort on the next service time.
+                * sort by key, that represents service time.
                 */
-               if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
+               if (time_before(rb_key, __cfqq->rb_key))
                        n = &(*p)->rb_left;
-               else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
-                       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 (time_before(rb_key, __cfqq->rb_key))
-                       n = &(*p)->rb_left;
-               else
+               else {
                        n = &(*p)->rb_right;
-
-               if (n == &(*p)->rb_right)
                        left = 0;
+               }
 
                p = n;
        }
 
        if (left)
-               cfqd->service_tree.left = &cfqq->rb_node;
+               service_tree->left = &cfqq->rb_node;
 
        cfqq->rb_key = rb_key;
        rb_link_node(&cfqq->rb_node, parent, p);
-       rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
+       rb_insert_color(&cfqq->rb_node, &service_tree->rb);
+       service_tree->count++;
 }
 
 static struct cfq_queue *
@@ -683,8 +790,10 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        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, &cfqd->service_tree);
+       if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
+               cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+               cfqq->service_tree = NULL;
+       }
        if (cfqq->p_root) {
                rb_erase(&cfqq->p_node, cfqq->p_root);
                cfqq->p_root = NULL;
@@ -945,10 +1054,12 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
  */
 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
 {
-       if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
-               return NULL;
+       struct cfq_rb_root *service_tree =
+               service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd);
 
-       return cfq_rb_first(&cfqd->service_tree);
+       if (RB_EMPTY_ROOT(&service_tree->rb))
+               return NULL;
+       return cfq_rb_first(service_tree);
 }
 
 /*
@@ -1065,9 +1176,45 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
        if (CFQQ_SEEKY(cfqq))
                return NULL;
 
+       /*
+        * Do not merge queues of different priority classes
+        */
+       if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
+               return NULL;
+
        return cfqq;
 }
 
+/*
+ * Determine whether we should enforce idle window for this queue.
+ */
+
+static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+       enum wl_prio_t prio = cfqq_prio(cfqq);
+       struct cfq_rb_root *service_tree = cfqq->service_tree;
+
+       /* We never do for idle class queues. */
+       if (prio == IDLE_WORKLOAD)
+               return false;
+
+       /* We do for queues that were marked with idle window flag. */
+       if (cfq_cfqq_idle_window(cfqq))
+               return true;
+
+       /*
+        * Otherwise, we do only if they are the last ones
+        * in their service tree.
+        */
+       if (!service_tree)
+               service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd);
+
+       if (service_tree->count == 0)
+               return true;
+
+       return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq);
+}
+
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq = cfqd->active_queue;
@@ -1088,7 +1235,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
        /*
         * idle is disabled, either manually or by past process history
         */
-       if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
+       if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
                return;
 
        /*
@@ -1115,14 +1262,20 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 
        cfq_mark_cfqq_wait_request(cfqq);
 
-       /*
-        * we don't want to idle for seeks, but we do want to allow
-        * fair distribution of slice time for a process doing back-to-back
-        * seeks. so allow a little bit of time for him to submit a new rq
-        */
        sl = cfqd->cfq_slice_idle;
-       if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))
+       /* are we servicing noidle tree, and there are more queues?
+        * non-rotational or NCQ: no idle
+        * non-NCQ rotational : very small idle, to allow
+        *     fair distribution of slice time for a process doing back-to-back
+        *     seeks.
+        */
+       if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
+           service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd)
+               ->count > 0) {
+               if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)
+                       return;
                sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
+       }
 
        mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
        cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
@@ -1226,6 +1379,106 @@ 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, enum wl_prio_t prio,
+                                   bool prio_changed)
+{
+       struct cfq_queue *queue;
+       int i;
+       bool key_valid = false;
+       unsigned long lowest_key = 0;
+       enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
+
+       if (prio_changed) {
+               /*
+                * When priorities switched, we prefer starting
+                * from SYNC_NOIDLE (first choice), or just SYNC
+                * over ASYNC
+                */
+               if (service_tree_for(prio, cur_best, cfqd)->count)
+                       return cur_best;
+               cur_best = SYNC_WORKLOAD;
+               if (service_tree_for(prio, cur_best, cfqd)->count)
+                       return cur_best;
+
+               return ASYNC_WORKLOAD;
+       }
+
+       for (i = 0; i < 3; ++i) {
+               /* otherwise, select the one with lowest rb_key */
+               queue = cfq_rb_first(service_tree_for(prio, i, cfqd));
+               if (queue &&
+                   (!key_valid || time_before(queue->rb_key, lowest_key))) {
+                       lowest_key = queue->rb_key;
+                       cur_best = i;
+                       key_valid = true;
+               }
+       }
+
+       return cur_best;
+}
+
+static void choose_service_tree(struct cfq_data *cfqd)
+{
+       enum wl_prio_t previous_prio = cfqd->serving_prio;
+       bool prio_changed;
+       unsigned slice;
+       unsigned count;
+
+       /* Choose next priority. RT > BE > IDLE */
+       if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
+               cfqd->serving_prio = RT_WORKLOAD;
+       else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd))
+               cfqd->serving_prio = BE_WORKLOAD;
+       else {
+               cfqd->serving_prio = IDLE_WORKLOAD;
+               cfqd->workload_expires = jiffies + 1;
+               return;
+       }
+
+       /*
+        * For RT and BE, we have to choose also the type
+        * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
+        * expiration time
+        */
+       prio_changed = (cfqd->serving_prio != previous_prio);
+       count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
+               ->count;
+
+       /*
+        * If priority didn't change, check workload expiration,
+        * and that we still have other queues ready
+        */
+       if (!prio_changed && count &&
+           !time_after(jiffies, cfqd->workload_expires))
+               return;
+
+       /* otherwise select new workload type */
+       cfqd->serving_type =
+               cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed);
+       count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
+               ->count;
+
+       /*
+        * the workload slice is computed as a fraction of target latency
+        * proportional to the number of queues in that workload, over
+        * all the queues in the same priority class
+        */
+       slice = cfq_target_latency * count /
+               max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio],
+                     cfq_busy_queues_wl(cfqd->serving_prio, cfqd));
+
+       if (cfqd->serving_type == ASYNC_WORKLOAD)
+               /* async workload slice is scaled down according to
+                * the sync/async slice ratio. */
+               slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
+       else
+               /* sync workload slice is at least 2 * cfq_slice_idle */
+               slice = max(slice, 2 * cfqd->cfq_slice_idle);
+
+       slice = max_t(unsigned, slice, CFQ_MIN_TT);
+       cfqd->workload_expires = jiffies + slice;
+}
+
 /*
  * Select a queue for service. If we have a current active queue,
  * check whether to continue servicing it, or retrieve and set a new one.
@@ -1270,7 +1523,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
         * conditions to happen (or time out) before selecting a new queue.
         */
        if (timer_pending(&cfqd->idle_slice_timer) ||
-           (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
+           (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
                cfqq = NULL;
                goto keep_queue;
        }
@@ -1278,6 +1531,13 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 expire:
        cfq_slice_expired(cfqd, 0);
 new_queue:
+       /*
+        * Current queue expired. Check if we have to switch to a new
+        * service tree
+        */
+       if (!new_cfqq)
+               choose_service_tree(cfqd);
+
        cfqq = cfq_set_active_queue(cfqd, new_cfqq);
 keep_queue:
        return cfqq;
@@ -1304,8 +1564,14 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq;
        int dispatched = 0;
-
-       while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
+       int i, j;
+       for (i = 0; i < 2; ++i)
+               for (j = 0; j < 3; ++j)
+                       while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j]))
+                               != NULL)
+                               dispatched += __cfq_forced_dispatch_cfqq(cfqq);
+
+       while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL)
                dispatched += __cfq_forced_dispatch_cfqq(cfqq);
 
        cfq_slice_expired(cfqd, 0);
@@ -1323,7 +1589,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        /*
         * Drain async requests before we start sync IO
         */
-       if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
+       if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
                return false;
 
        /*
@@ -2086,13 +2352,10 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
 
        if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-           (!cfqd->cfq_latency && cfqd->hw_tag && CFQQ_SEEKY(cfqq)))
+           (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)))
                enable_idle = 0;
        else if (sample_valid(cic->ttime_samples)) {
-               unsigned int slice_idle = cfqd->cfq_slice_idle;
-               if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))
-                       slice_idle = msecs_to_jiffies(CFQ_MIN_TT);
-               if (cic->ttime_mean > slice_idle)
+               if (cic->ttime_mean > cfqd->cfq_slice_idle)
                        enable_idle = 0;
                else
                        enable_idle = 1;
@@ -2130,6 +2393,10 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
        if (cfq_class_idle(cfqq))
                return true;
 
+       if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD
+           && new_cfqq->service_tree == cfqq->service_tree)
+               return true;
+
        /*
         * if the new request is sync, but the currently running queue is
         * not, let the sync request have priority.
@@ -2243,10 +2510,9 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
        cfq_log_cfqq(cfqd, cfqq, "insert_request");
        cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
 
-       cfq_add_rq_rb(rq);
-
        rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
        list_add_tail(&rq->queuelist, &cfqq->fifo);
+       cfq_add_rq_rb(rq);
 
        cfq_rq_enqueued(cfqd, cfqq, rq);
 }
@@ -2645,13 +2911,16 @@ static void cfq_exit_queue(struct elevator_queue *e)
 static void *cfq_init_queue(struct request_queue *q)
 {
        struct cfq_data *cfqd;
-       int i;
+       int i, j;
 
        cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
        if (!cfqd)
                return NULL;
 
-       cfqd->service_tree = CFQ_RB_ROOT;
+       for (i = 0; i < 2; ++i)
+               for (j = 0; j < 3; ++j)
+                       cfqd->service_trees[i][j] = CFQ_RB_ROOT;
+       cfqd->service_tree_idle = CFQ_RB_ROOT;
 
        /*
         * Not strictly needed (since RB_ROOT just clears the node and we