]> nv-tegra.nvidia Code Review - linux-2.6.git/blobdiff - block/cfq-iosched.c
bootmem: micro optimize freeing pages in bulk
[linux-2.6.git] / block / cfq-iosched.c
index 5d0349d602febf12a059f4a8180c78ba1a1c9772..3548705b04e482a4405097217011256105c4bdca 100644 (file)
@@ -54,9 +54,9 @@ static const int cfq_hist_divisor = 4;
 #define CFQQ_SEEKY(cfqq)       (hweight32(cfqq->seek_history) > 32/8)
 
 #define RQ_CIC(rq)             \
-       ((struct cfq_io_context *) (rq)->elevator_private)
-#define RQ_CFQQ(rq)            (struct cfq_queue *) ((rq)->elevator_private2)
-#define RQ_CFQG(rq)            (struct cfq_group *) ((rq)->elevator_private3)
+       ((struct cfq_io_context *) (rq)->elevator_private[0])
+#define RQ_CFQQ(rq)            (struct cfq_queue *) ((rq)->elevator_private[1])
+#define RQ_CFQG(rq)            (struct cfq_group *) ((rq)->elevator_private[2])
 
 static struct kmem_cache *cfq_pool;
 static struct kmem_cache *cfq_ioc_pool;
@@ -87,16 +87,17 @@ struct cfq_rb_root {
        unsigned count;
        unsigned total_weight;
        u64 min_vdisktime;
+       struct cfq_ttime ttime;
 };
-#define CFQ_RB_ROOT    (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
-                       .count = 0, .min_vdisktime = 0, }
+#define CFQ_RB_ROOT    (struct cfq_rb_root) { .rb = RB_ROOT, \
+                       .ttime = {.last_end_request = jiffies,},}
 
 /*
  * Per process-grouping structure
  */
 struct cfq_queue {
        /* reference count */
-       atomic_t ref;
+       int ref;
        /* various state flags, see below */
        unsigned int flags;
        /* parent cfq_data */
@@ -129,14 +130,14 @@ struct cfq_queue {
        unsigned long slice_end;
        long slice_resid;
 
-       /* pending metadata requests */
-       int meta_pending;
+       /* pending priority requests */
+       int prio_pending;
        /* number of requests that are on the dispatch list or inside driver */
        int dispatched;
 
        /* io prio of this group */
        unsigned short ioprio, org_ioprio;
-       unsigned short ioprio_class, org_ioprio_class;
+       unsigned short ioprio_class;
 
        pid_t pid;
 
@@ -146,7 +147,6 @@ struct cfq_queue {
        struct cfq_rb_root *service_tree;
        struct cfq_queue *new_cfqq;
        struct cfq_group *cfqg;
-       struct cfq_group *orig_cfqg;
        /* Number of sectors dispatched from queue in single dispatch round */
        unsigned long nr_sectors;
 };
@@ -179,12 +179,14 @@ struct cfq_group {
        /* group service_tree key */
        u64 vdisktime;
        unsigned int weight;
+       unsigned int new_weight;
+       bool needs_update;
 
        /* number of cfqq currently on this group */
        int nr_cfqq;
 
        /*
-        * Per group busy queus average. Useful for workload slice calc. We
+        * Per group busy queues average. Useful for workload slice calc. We
         * create the array for each prio class but at run time it is used
         * only for RT and BE class and slot for IDLE class remains unused.
         * This is primarily done to avoid confusion and a gcc warning.
@@ -207,10 +209,11 @@ struct cfq_group {
        struct blkio_group blkg;
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
        struct hlist_node cfqd_node;
-       atomic_t ref;
+       int ref;
 #endif
        /* number of requests that are on the dispatch list or inside driver */
        int dispatched;
+       struct cfq_ttime ttime;
 };
 
 /*
@@ -238,6 +241,7 @@ struct cfq_data {
        struct rb_root prio_trees[CFQ_PRIO_LISTS];
 
        unsigned int busy_queues;
+       unsigned int busy_sync_queues;
 
        int rq_in_driver;
        int rq_in_flight[2];
@@ -285,7 +289,6 @@ struct cfq_data {
        unsigned int cfq_slice_idle;
        unsigned int cfq_group_idle;
        unsigned int cfq_latency;
-       unsigned int cfq_group_isolation;
 
        unsigned int cic_index;
        struct list_head cic_list;
@@ -299,7 +302,9 @@ struct cfq_data {
 
        /* List of cfq groups being managed on this device*/
        struct hlist_head cfqg_list;
-       struct rcu_head rcu;
+
+       /* Number of groups which are on blkcg->blkg_list */
+       unsigned int nr_blkcg_linked_grps;
 };
 
 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
@@ -366,16 +371,16 @@ CFQ_CFQQ_FNS(wait_busy);
 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
        blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
                        cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
-                       blkg_path(&(cfqq)->cfqg->blkg), ##args);
+                       blkg_path(&(cfqq)->cfqg->blkg), ##args)
 
 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)                         \
        blk_add_trace_msg((cfqd)->queue, "%s " fmt,                     \
-                               blkg_path(&(cfqg)->blkg), ##args);      \
+                               blkg_path(&(cfqg)->blkg), ##args)       \
 
 #else
 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
        blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
-#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)         do {} while (0);
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)         do {} while (0)
 #endif
 #define cfq_log(cfqd, fmt, args...)    \
        blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
@@ -390,6 +395,18 @@ CFQ_CFQQ_FNS(wait_busy);
                        j++, st = i < IDLE_WORKLOAD ? \
                        &cfqg->service_trees[i][j]: NULL) \
 
+static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
+       struct cfq_ttime *ttime, bool group_idle)
+{
+       unsigned long slice;
+       if (!sample_valid(ttime->ttime_samples))
+               return false;
+       if (group_idle)
+               slice = cfqd->cfq_group_idle;
+       else
+               slice = cfqd->cfq_slice_idle;
+       return ttime->ttime_mean > slice;
+}
 
 static inline bool iops_mode(struct cfq_data *cfqd)
 {
@@ -501,13 +518,6 @@ static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
        }
 }
 
-static int cfq_queue_empty(struct request_queue *q)
-{
-       struct cfq_data *cfqd = q->elevator->elevator_data;
-
-       return !cfqd->rq_queued;
-}
-
 /*
  * Scale schedule slice based on io priority. Use the sync time slice only
  * if a queue is marked sync and has sync io queued. A sync queue with async
@@ -558,15 +568,13 @@ static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
 
 static void update_min_vdisktime(struct cfq_rb_root *st)
 {
-       u64 vdisktime = st->min_vdisktime;
        struct cfq_group *cfqg;
 
        if (st->left) {
                cfqg = rb_entry_cfqg(st->left);
-               vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
+               st->min_vdisktime = max_vdisktime(st->min_vdisktime,
+                                                 cfqg->vdisktime);
        }
-
-       st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
 }
 
 /*
@@ -598,8 +606,8 @@ cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
        return cfq_target_latency * cfqg->weight / st->total_weight;
 }
 
-static inline void
-cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+static inline unsigned
+cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
        unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
        if (cfqd->cfq_latency) {
@@ -625,6 +633,14 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
                                    low_slice);
                }
        }
+       return slice;
+}
+
+static inline void
+cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+       unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
+
        cfqq->slice_start = jiffies;
        cfqq->slice_end = jiffies + slice;
        cfqq->allocated_slice = slice;
@@ -665,15 +681,11 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
        if (rq2 == NULL)
                return rq1;
 
-       if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-               return rq1;
-       else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-               return rq2;
-       if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-               return rq1;
-       else if ((rq2->cmd_flags & REQ_META) &&
-                !(rq1->cmd_flags & REQ_META))
-               return rq2;
+       if (rq_is_sync(rq1) != rq_is_sync(rq2))
+               return rq_is_sync(rq1) ? rq1 : rq2;
+
+       if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
+               return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
 
        s1 = blk_rq_pos(rq1);
        s2 = blk_rq_pos(rq2);
@@ -855,7 +867,27 @@ __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
 }
 
 static void
-cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
+cfq_update_group_weight(struct cfq_group *cfqg)
+{
+       BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
+       if (cfqg->needs_update) {
+               cfqg->weight = cfqg->new_weight;
+               cfqg->needs_update = false;
+       }
+}
+
+static void
+cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+       BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
+
+       cfq_update_group_weight(cfqg);
+       __cfq_group_service_tree_add(st, cfqg);
+       st->total_weight += cfqg->weight;
+}
+
+static void
+cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
 {
        struct cfq_rb_root *st = &cfqd->grp_service_tree;
        struct cfq_group *__cfqg;
@@ -868,7 +900,7 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
        /*
         * Currently put the group at the end. Later implement something
         * so that groups get lesser vtime based on their weights, so that
-        * if group does not loose all if it was not continously backlogged.
+        * if group does not loose all if it was not continuously backlogged.
         */
        n = rb_last(&st->rb);
        if (n) {
@@ -876,13 +908,19 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
                cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
        } else
                cfqg->vdisktime = st->min_vdisktime;
+       cfq_group_service_tree_add(st, cfqg);
+}
 
-       __cfq_group_service_tree_add(st, cfqg);
-       st->total_weight += cfqg->weight;
+static void
+cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+       st->total_weight -= cfqg->weight;
+       if (!RB_EMPTY_NODE(&cfqg->rb_node))
+               cfq_rb_erase(&cfqg->rb_node, st);
 }
 
 static void
-cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
+cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
 {
        struct cfq_rb_root *st = &cfqd->grp_service_tree;
 
@@ -894,14 +932,13 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
                return;
 
        cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
-       st->total_weight -= cfqg->weight;
-       if (!RB_EMPTY_NODE(&cfqg->rb_node))
-               cfq_rb_erase(&cfqg->rb_node, st);
+       cfq_group_service_tree_del(st, cfqg);
        cfqg->saved_workload_slice = 0;
        cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
 }
 
-static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
+static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
+                                               unsigned int *unaccounted_time)
 {
        unsigned int slice_used;
 
@@ -920,8 +957,13 @@ static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
                                        1);
        } else {
                slice_used = jiffies - cfqq->slice_start;
-               if (slice_used > cfqq->allocated_slice)
+               if (slice_used > cfqq->allocated_slice) {
+                       *unaccounted_time = slice_used - cfqq->allocated_slice;
                        slice_used = cfqq->allocated_slice;
+               }
+               if (time_after(cfqq->slice_start, cfqq->dispatch_start))
+                       *unaccounted_time += cfqq->slice_start -
+                                       cfqq->dispatch_start;
        }
 
        return slice_used;
@@ -931,12 +973,12 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
                                struct cfq_queue *cfqq)
 {
        struct cfq_rb_root *st = &cfqd->grp_service_tree;
-       unsigned int used_sl, charge;
+       unsigned int used_sl, charge, unaccounted_sl = 0;
        int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
                        - cfqg->service_tree_idle.count;
 
        BUG_ON(nr_sync < 0);
-       used_sl = charge = cfq_cfqq_slice_usage(cfqq);
+       used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
 
        if (iops_mode(cfqd))
                charge = cfqq->slice_dispatch;
@@ -944,9 +986,10 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
                charge = cfqq->allocated_slice;
 
        /* Can't update vdisktime while group is on service tree */
-       cfq_rb_erase(&cfqg->rb_node, st);
+       cfq_group_service_tree_del(st, cfqg);
        cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
-       __cfq_group_service_tree_add(st, cfqg);
+       /* If a new weight was requested, update now, off tree */
+       cfq_group_service_tree_add(st, cfqg);
 
        /* This group is being expired. Save the context */
        if (time_after(cfqd->workload_expires, jiffies)) {
@@ -959,10 +1002,12 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
 
        cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
                                        st->min_vdisktime);
-       cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
-                       " sect=%u", used_sl, cfqq->slice_dispatch, charge,
-                       iops_mode(cfqd), cfqq->nr_sectors);
-       cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
+       cfq_log_cfqq(cfqq->cfqd, cfqq,
+                    "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
+                    used_sl, cfqq->slice_dispatch, charge,
+                    iops_mode(cfqd), cfqq->nr_sectors);
+       cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
+                                         unaccounted_sl);
        cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
 }
 
@@ -974,92 +1019,165 @@ static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
        return NULL;
 }
 
-void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
-                                       unsigned int weight)
+static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
+                                         unsigned int weight)
 {
-       cfqg_of_blkg(blkg)->weight = weight;
+       struct cfq_group *cfqg = cfqg_of_blkg(blkg);
+       cfqg->new_weight = weight;
+       cfqg->needs_update = true;
 }
 
-static struct cfq_group *
-cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
+static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
+                       struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
 {
-       struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
-       struct cfq_group *cfqg = NULL;
-       void *key = cfqd;
-       int i, j;
-       struct cfq_rb_root *st;
        struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
        unsigned int major, minor;
 
-       cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
-       if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+       /*
+        * Add group onto cgroup list. It might happen that bdi->dev is
+        * not initialized yet. Initialize this new group without major
+        * and minor info and this info will be filled in once a new thread
+        * comes for IO.
+        */
+       if (bdi->dev) {
                sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
-               cfqg->blkg.dev = MKDEV(major, minor);
-               goto done;
-       }
-       if (cfqg || !create)
-               goto done;
+               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+                                       (void *)cfqd, MKDEV(major, minor));
+       } else
+               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+                                       (void *)cfqd, 0);
+
+       cfqd->nr_blkcg_linked_grps++;
+       cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
+
+       /* Add group on cfqd list */
+       hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+}
+
+/*
+ * Should be called from sleepable context. No request queue lock as per
+ * cpu stats are allocated dynamically and alloc_percpu needs to be called
+ * from sleepable context.
+ */
+static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
+{
+       struct cfq_group *cfqg = NULL;
+       int i, j, ret;
+       struct cfq_rb_root *st;
 
        cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
        if (!cfqg)
-               goto done;
+               return NULL;
 
        for_each_cfqg_st(cfqg, i, j, st)
                *st = CFQ_RB_ROOT;
        RB_CLEAR_NODE(&cfqg->rb_node);
 
+       cfqg->ttime.last_end_request = jiffies;
+
        /*
         * Take the initial reference that will be released on destroy
         * This can be thought of a joint reference by cgroup and
         * elevator which will be dropped by either elevator exit
         * or cgroup deletion path depending on who is exiting first.
         */
-       atomic_set(&cfqg->ref, 1);
+       cfqg->ref = 1;
+
+       ret = blkio_alloc_blkg_stats(&cfqg->blkg);
+       if (ret) {
+               kfree(cfqg);
+               return NULL;
+       }
+
+       return cfqg;
+}
+
+static struct cfq_group *
+cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
+{
+       struct cfq_group *cfqg = NULL;
+       void *key = cfqd;
+       struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
+       unsigned int major, minor;
 
        /*
-        * Add group onto cgroup list. It might happen that bdi->dev is
-        * not initiliazed yet. Initialize this new group without major
-        * and minor info and this info will be filled in once a new thread
-        * comes for IO. See code above.
+        * This is the common case when there are no blkio cgroups.
+        * Avoid lookup in this case
         */
-       if (bdi->dev) {
-               sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
-               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
-                                       MKDEV(major, minor));
-       } else
-               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
-                                       0);
-
-       cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
+       if (blkcg == &blkio_root_cgroup)
+               cfqg = &cfqd->root_group;
+       else
+               cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
 
-       /* Add group on cfqd list */
-       hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+       if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+               sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+               cfqg->blkg.dev = MKDEV(major, minor);
+       }
 
-done:
        return cfqg;
 }
 
 /*
- * Search for the cfq group current task belongs to. If create = 1, then also
- * create the cfq group if it does not exist. request_queue lock must be held.
+ * Search for the cfq group current task belongs to. request_queue lock must
+ * be held.
  */
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
 {
-       struct cgroup *cgroup;
-       struct cfq_group *cfqg = NULL;
+       struct blkio_cgroup *blkcg;
+       struct cfq_group *cfqg = NULL, *__cfqg = NULL;
+       struct request_queue *q = cfqd->queue;
+
+       rcu_read_lock();
+       blkcg = task_blkio_cgroup(current);
+       cfqg = cfq_find_cfqg(cfqd, blkcg);
+       if (cfqg) {
+               rcu_read_unlock();
+               return cfqg;
+       }
+
+       /*
+        * Need to allocate a group. Allocation of group also needs allocation
+        * of per cpu stats which in-turn takes a mutex() and can block. Hence
+        * we need to drop rcu lock and queue_lock before we call alloc.
+        *
+        * Not taking any queue reference here and assuming that queue is
+        * around by the time we return. CFQ queue allocation code does
+        * the same. It might be racy though.
+        */
+
+       rcu_read_unlock();
+       spin_unlock_irq(q->queue_lock);
+
+       cfqg = cfq_alloc_cfqg(cfqd);
+
+       spin_lock_irq(q->queue_lock);
 
        rcu_read_lock();
-       cgroup = task_cgroup(current, blkio_subsys_id);
-       cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
-       if (!cfqg && create)
+       blkcg = task_blkio_cgroup(current);
+
+       /*
+        * If some other thread already allocated the group while we were
+        * not holding queue lock, free up the group
+        */
+       __cfqg = cfq_find_cfqg(cfqd, blkcg);
+
+       if (__cfqg) {
+               kfree(cfqg);
+               rcu_read_unlock();
+               return __cfqg;
+       }
+
+       if (!cfqg)
                cfqg = &cfqd->root_group;
+
+       cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
        rcu_read_unlock();
        return cfqg;
 }
 
 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
 {
-       atomic_inc(&cfqg->ref);
+       cfqg->ref++;
        return cfqg;
 }
 
@@ -1071,7 +1189,7 @@ static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
 
        cfqq->cfqg = cfqg;
        /* cfqq reference on cfqg */
-       atomic_inc(&cfqq->cfqg->ref);
+       cfqq->cfqg->ref++;
 }
 
 static void cfq_put_cfqg(struct cfq_group *cfqg)
@@ -1079,11 +1197,13 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
        struct cfq_rb_root *st;
        int i, j;
 
-       BUG_ON(atomic_read(&cfqg->ref) <= 0);
-       if (!atomic_dec_and_test(&cfqg->ref))
+       BUG_ON(cfqg->ref <= 0);
+       cfqg->ref--;
+       if (cfqg->ref)
                return;
        for_each_cfqg_st(cfqg, i, j, st)
                BUG_ON(!RB_EMPTY_ROOT(&st->rb));
+       free_percpu(cfqg->blkg.stats_cpu);
        kfree(cfqg);
 }
 
@@ -1094,6 +1214,9 @@ static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
 
        hlist_del_init(&cfqg->cfqd_node);
 
+       BUG_ON(cfqd->nr_blkcg_linked_grps <= 0);
+       cfqd->nr_blkcg_linked_grps--;
+
        /*
         * Put the reference taken at the time of creation so that when all
         * queues are gone, group can be destroyed.
@@ -1131,7 +1254,7 @@ static void cfq_release_cfq_groups(struct cfq_data *cfqd)
  * it should not be NULL as even if elevator was exiting, cgroup deltion
  * path got to it first.
  */
-void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
+static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
 {
        unsigned long  flags;
        struct cfq_data *cfqd = key;
@@ -1142,7 +1265,7 @@ void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
 }
 
 #else /* GROUP_IOSCHED */
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
 {
        return &cfqd->root_group;
 }
@@ -1176,33 +1299,6 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        struct cfq_rb_root *service_tree;
        int left;
        int new_cfqq = 1;
-       int group_changed = 0;
-
-#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))
-                       cfq_group_service_tree_del(cfqd, cfqq->cfqg);
-               cfqq->orig_cfqg = cfqq->cfqg;
-               cfqq->cfqg = &cfqd->root_group;
-               atomic_inc(&cfqd->root_group.ref);
-               group_changed = 1;
-       } else if (!cfqd->cfq_group_isolation
-                  && 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))
-                       cfq_group_service_tree_del(cfqd, cfqq->cfqg);
-               cfq_put_cfqg(cfqq->cfqg);
-               cfqq->cfqg = cfqq->orig_cfqg;
-               cfqq->orig_cfqg = NULL;
-               group_changed = 1;
-               cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
-       }
-#endif
 
        service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
                                                cfqq_type(cfqq));
@@ -1273,9 +1369,9 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        rb_link_node(&cfqq->rb_node, parent, p);
        rb_insert_color(&cfqq->rb_node, &service_tree->rb);
        service_tree->count++;
-       if ((add_front || !new_cfqq) && !group_changed)
+       if (add_front || !new_cfqq)
                return;
-       cfq_group_service_tree_add(cfqd, cfqq->cfqg);
+       cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
 }
 
 static struct cfq_queue *
@@ -1363,6 +1459,8 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        BUG_ON(cfq_cfqq_on_rr(cfqq));
        cfq_mark_cfqq_on_rr(cfqq);
        cfqd->busy_queues++;
+       if (cfq_cfqq_sync(cfqq))
+               cfqd->busy_sync_queues++;
 
        cfq_resort_rr_list(cfqd, cfqq);
 }
@@ -1386,9 +1484,11 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
                cfqq->p_root = NULL;
        }
 
-       cfq_group_service_tree_del(cfqd, cfqq->cfqg);
+       cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
        BUG_ON(!cfqd->busy_queues);
        cfqd->busy_queues--;
+       if (cfq_cfqq_sync(cfqq))
+               cfqd->busy_sync_queues--;
 }
 
 /*
@@ -1421,16 +1521,11 @@ 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, *prev;
+       struct request *prev;
 
        cfqq->queued[rq_is_sync(rq)]++;
 
-       /*
-        * looks a little odd, but the first insert might return an alias.
-        * if that happens, put the alias on the dispatch list
-        */
-       while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
-               cfq_dispatch_insert(cfqd->queue, __alias);
+       elv_rb_add(&cfqq->sort_list, rq);
 
        if (!cfq_cfqq_on_rr(cfqq))
                cfq_add_cfqq_rr(cfqd, cfqq);
@@ -1517,9 +1612,9 @@ static void cfq_remove_request(struct request *rq)
        cfqq->cfqd->rq_queued--;
        cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
                                        rq_data_dir(rq), rq_is_sync(rq));
-       if (rq->cmd_flags & REQ_META) {
-               WARN_ON(!cfqq->meta_pending);
-               cfqq->meta_pending--;
+       if (rq->cmd_flags & REQ_PRIO) {
+               WARN_ON(!cfqq->prio_pending);
+               cfqq->prio_pending--;
        }
 }
 
@@ -1560,6 +1655,8 @@ cfq_merged_requests(struct request_queue *q, struct request *rq,
                    struct request *next)
 {
        struct cfq_queue *cfqq = RQ_CFQQ(rq);
+       struct cfq_data *cfqd = q->elevator->elevator_data;
+
        /*
         * reposition in fifo if next is older than rq
         */
@@ -1574,6 +1671,16 @@ cfq_merged_requests(struct request_queue *q, struct request *rq,
        cfq_remove_request(next);
        cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
                                        rq_data_dir(next), rq_is_sync(next));
+
+       cfqq = RQ_CFQQ(next);
+       /*
+        * all requests of this queue are merged to other queues, delete it
+        * from the service tree. If it's the active_queue,
+        * cfq_dispatch_requests() will choose to expire it or do idle
+        */
+       if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
+           cfqq != cfqd->active_queue)
+               cfq_del_cfqq_rr(cfqd, cfqq);
 }
 
 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
@@ -1660,8 +1767,11 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        /*
         * store what was left of this slice, if the queue idled/timed out
         */
-       if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
-               cfqq->slice_resid = cfqq->slice_end - jiffies;
+       if (timed_out) {
+               if (cfq_cfqq_slice_new(cfqq))
+                       cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
+               else
+                       cfqq->slice_resid = cfqq->slice_end - jiffies;
                cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
        }
 
@@ -1885,7 +1995,8 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         * Otherwise, we do only if they are the last ones
         * in their service tree.
         */
-       if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
+       if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
+          !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
                return true;
        cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
                        service_tree->count);
@@ -1938,10 +2049,10 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
         * slice, then don't idle. This avoids overrunning the allotted
         * time slice.
         */
-       if (sample_valid(cic->ttime_samples) &&
-           (cfqq->slice_end - jiffies < cic->ttime_mean)) {
-               cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
-                               cic->ttime_mean);
+       if (sample_valid(cic->ttime.ttime_samples) &&
+           (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
+               cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
+                            cic->ttime.ttime_mean);
                return;
        }
 
@@ -2014,7 +2125,7 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
        WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
 
-       return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
+       return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
 }
 
 /*
@@ -2025,7 +2136,7 @@ static int cfqq_process_refs(struct cfq_queue *cfqq)
        int process_refs, io_refs;
 
        io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
-       process_refs = atomic_read(&cfqq->ref) - io_refs;
+       process_refs = cfqq->ref - io_refs;
        BUG_ON(process_refs < 0);
        return process_refs;
 }
@@ -2065,10 +2176,10 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
         */
        if (new_process_refs >= process_refs) {
                cfqq->new_cfqq = new_cfqq;
-               atomic_add(process_refs, &new_cfqq->ref);
+               new_cfqq->ref += process_refs;
        } else {
                new_cfqq->new_cfqq = cfqq;
-               atomic_add(new_process_refs, &cfqq->ref);
+               cfqq->ref += new_process_refs;
        }
 }
 
@@ -2101,12 +2212,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
        unsigned count;
        struct cfq_rb_root *st;
        unsigned group_slice;
-
-       if (!cfqg) {
-               cfqd->serving_prio = IDLE_WORKLOAD;
-               cfqd->workload_expires = jiffies + 1;
-               return;
-       }
+       enum wl_prio_t original_prio = cfqd->serving_prio;
 
        /* Choose next priority. RT > BE > IDLE */
        if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
@@ -2119,6 +2225,9 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
                return;
        }
 
+       if (original_prio != cfqd->serving_prio)
+               goto new_workload;
+
        /*
         * For RT and BE, we have to choose also the type
         * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
@@ -2133,6 +2242,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
        if (count && !time_after(jiffies, cfqd->workload_expires))
                return;
 
+new_workload:
        /* otherwise select new workload type */
        cfqd->serving_type =
                cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
@@ -2298,8 +2408,9 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
         * this group, wait for requests to complete.
         */
 check_group_idle:
-       if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
-           && cfqq->cfqg->dispatched) {
+       if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
+           cfqq->cfqg->dispatched &&
+           !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
                cfqq = NULL;
                goto keep_queue;
        }
@@ -2394,22 +2505,34 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         * Does this cfqq already have too much IO in flight?
         */
        if (cfqq->dispatched >= max_dispatch) {
+               bool promote_sync = false;
                /*
                 * idle queue must always only have a single IO in flight
                 */
                if (cfq_class_idle(cfqq))
                        return false;
 
+               /*
+                * If there is only one sync queue
+                * we can ignore async queue here and give the sync
+                * queue no dispatch limit. The reason is a sync queue can
+                * preempt async queue, limiting the sync queue doesn't make
+                * sense. This is useful for aiostress test.
+                */
+               if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
+                       promote_sync = true;
+
                /*
                 * We have other queues, don't allow more IO from this one
                 */
-               if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
+               if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
+                               !promote_sync)
                        return false;
 
                /*
                 * Sole queue user, no limit
                 */
-               if (cfqd->busy_queues == 1)
+               if (cfqd->busy_queues == 1 || promote_sync)
                        max_dispatch = -1;
                else
                        /*
@@ -2531,18 +2654,18 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
 static void cfq_put_queue(struct cfq_queue *cfqq)
 {
        struct cfq_data *cfqd = cfqq->cfqd;
-       struct cfq_group *cfqg, *orig_cfqg;
+       struct cfq_group *cfqg;
 
-       BUG_ON(atomic_read(&cfqq->ref) <= 0);
+       BUG_ON(cfqq->ref <= 0);
 
-       if (!atomic_dec_and_test(&cfqq->ref))
+       cfqq->ref--;
+       if (cfqq->ref)
                return;
 
        cfq_log_cfqq(cfqd, cfqq, "put_queue");
        BUG_ON(rb_first(&cfqq->sort_list));
        BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
        cfqg = cfqq->cfqg;
-       orig_cfqg = cfqq->orig_cfqg;
 
        if (unlikely(cfqd->active_queue == cfqq)) {
                __cfq_slice_expired(cfqd, cfqq, 0);
@@ -2552,33 +2675,23 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
        BUG_ON(cfq_cfqq_on_rr(cfqq));
        kmem_cache_free(cfq_pool, cfqq);
        cfq_put_cfqg(cfqg);
-       if (orig_cfqg)
-               cfq_put_cfqg(orig_cfqg);
 }
 
 /*
- * Must always be called with the rcu_read_lock() held
+ * Call func for each cic attached to this ioc.
  */
 static void
-__call_for_each_cic(struct io_context *ioc,
-                   void (*func)(struct io_context *, struct cfq_io_context *))
+call_for_each_cic(struct io_context *ioc,
+                 void (*func)(struct io_context *, struct cfq_io_context *))
 {
        struct cfq_io_context *cic;
        struct hlist_node *n;
 
+       rcu_read_lock();
+
        hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
                func(ioc, cic);
-}
 
-/*
- * Call func for each cic attached to this ioc.
- */
-static void
-call_for_each_cic(struct io_context *ioc,
-                 void (*func)(struct io_context *, struct cfq_io_context *))
-{
-       rcu_read_lock();
-       __call_for_each_cic(ioc, func);
        rcu_read_unlock();
 }
 
@@ -2639,7 +2752,7 @@ static void cfq_free_io_context(struct io_context *ioc)
         * should be ok to iterate over the known list, we will see all cic's
         * since no new ones are added.
         */
-       __call_for_each_cic(ioc, cic_free_func);
+       call_for_each_cic(ioc, cic_free_func);
 }
 
 static void cfq_put_cooperator(struct cfq_queue *cfqq)
@@ -2688,8 +2801,14 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
        smp_wmb();
        cic->key = cfqd_dead_key(cfqd);
 
-       if (ioc->ioc_data == cic)
+       rcu_read_lock();
+       if (rcu_dereference(ioc->ioc_data) == cic) {
+               rcu_read_unlock();
+               spin_lock(&ioc->lock);
                rcu_assign_pointer(ioc->ioc_data, NULL);
+               spin_unlock(&ioc->lock);
+       } else
+               rcu_read_unlock();
 
        if (cic->cfqq[BLK_RW_ASYNC]) {
                cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
@@ -2742,7 +2861,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
        cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
                                                        cfqd->queue->node);
        if (cic) {
-               cic->last_end_request = jiffies;
+               cic->ttime.last_end_request = jiffies;
                INIT_LIST_HEAD(&cic->queue_list);
                INIT_HLIST_NODE(&cic->cic_list);
                cic->dtor = cfq_free_io_context;
@@ -2792,7 +2911,6 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
         * elevate the priority of this queue
         */
        cfqq->org_ioprio = cfqq->ioprio;
-       cfqq->org_ioprio_class = cfqq->ioprio_class;
        cfq_clear_cfqq_prio_changed(cfqq);
 }
 
@@ -2838,7 +2956,7 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        RB_CLEAR_NODE(&cfqq->p_node);
        INIT_LIST_HEAD(&cfqq->fifo);
 
-       atomic_set(&cfqq->ref, 0);
+       cfqq->ref = 0;
        cfqq->cfqd = cfqd;
 
        cfq_mark_cfqq_prio_changed(cfqq);
@@ -2895,7 +3013,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
        struct cfq_group *cfqg;
 
 retry:
-       cfqg = cfq_get_cfqg(cfqd, 1);
+       cfqg = cfq_get_cfqg(cfqd);
        cic = cfq_cic_lookup(cfqd, ioc);
        /* cic always exists here */
        cfqq = cic_to_cfqq(cic, is_sync);
@@ -2974,11 +3092,11 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
         * pin the queue now that it's allocated, scheduler exit will prune it
         */
        if (!is_sync && !(*async_cfqq)) {
-               atomic_inc(&cfqq->ref);
+               cfqq->ref++;
                *async_cfqq = cfqq;
        }
 
-       atomic_inc(&cfqq->ref);
+       cfqq->ref++;
        return cfqq;
 }
 
@@ -2996,7 +3114,8 @@ cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
 
        spin_lock_irqsave(&ioc->lock, flags);
 
-       BUG_ON(ioc->ioc_data == cic);
+       BUG_ON(rcu_dereference_check(ioc->ioc_data,
+               lockdep_is_held(&ioc->lock)) == cic);
 
        radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
        hlist_del_rcu(&cic->cic_list);
@@ -3077,7 +3196,7 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
                }
        }
 
-       if (ret)
+       if (ret && ret != -EEXIST)
                printk(KERN_ERR "cfq: cic link failed!\n");
 
        return ret;
@@ -3093,6 +3212,7 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
        struct io_context *ioc = NULL;
        struct cfq_io_context *cic;
+       int ret;
 
        might_sleep_if(gfp_mask & __GFP_WAIT);
 
@@ -3100,6 +3220,7 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
        if (!ioc)
                return NULL;
 
+retry:
        cic = cfq_cic_lookup(cfqd, ioc);
        if (cic)
                goto out;
@@ -3108,7 +3229,12 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
        if (cic == NULL)
                goto err;
 
-       if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
+       ret = cfq_cic_link(cfqd, ioc, cic, gfp_mask);
+       if (ret == -EEXIST) {
+               /* someone has linked cic to ioc already */
+               cfq_cic_free(cic);
+               goto retry;
+       } else if (ret)
                goto err_free;
 
 out:
@@ -3129,14 +3255,28 @@ err:
 }
 
 static void
-cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
+__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
 {
-       unsigned long elapsed = jiffies - cic->last_end_request;
-       unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
+       unsigned long elapsed = jiffies - ttime->last_end_request;
+       elapsed = min(elapsed, 2UL * slice_idle);
 
-       cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
-       cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
-       cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
+       ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
+       ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
+       ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
+}
+
+static void
+cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+       struct cfq_io_context *cic)
+{
+       if (cfq_cfqq_sync(cfqq)) {
+               __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
+               __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
+                       cfqd->cfq_slice_idle);
+       }
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+       __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
+#endif
 }
 
 static void
@@ -3185,8 +3325,8 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
            (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
                enable_idle = 0;
-       else if (sample_valid(cic->ttime_samples)) {
-               if (cic->ttime_mean > cfqd->cfq_slice_idle)
+       else if (sample_valid(cic->ttime.ttime_samples)) {
+               if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
                        enable_idle = 0;
                else
                        enable_idle = 1;
@@ -3251,7 +3391,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
         * So both queues are sync. Let the new request get disk time if
         * it's a metadata request and the current queue is doing regular IO.
         */
-       if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
+       if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
                return true;
 
        /*
@@ -3283,9 +3423,18 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
  */
 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
+       struct cfq_queue *old_cfqq = cfqd->active_queue;
+
        cfq_log_cfqq(cfqd, cfqq, "preempt");
        cfq_slice_expired(cfqd, 1);
 
+       /*
+        * workload type is changed, don't save slice, otherwise preempt
+        * doesn't happen
+        */
+       if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
+               cfqq->cfqg->saved_workload_slice = 0;
+
        /*
         * Put the new queue at the front of the of the current list,
         * so we know that it will be selected next.
@@ -3309,10 +3458,10 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        struct cfq_io_context *cic = RQ_CIC(rq);
 
        cfqd->rq_queued++;
-       if (rq->cmd_flags & REQ_META)
-               cfqq->meta_pending++;
+       if (rq->cmd_flags & REQ_PRIO)
+               cfqq->prio_pending++;
 
-       cfq_update_io_thinktime(cfqd, cic);
+       cfq_update_io_thinktime(cfqd, cfqq, cic);
        cfq_update_io_seektime(cfqd, cfqq, rq);
        cfq_update_idle_window(cfqd, cfqq, cic);
 
@@ -3411,16 +3560,24 @@ static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
        struct cfq_io_context *cic = cfqd->active_cic;
 
+       /* If the queue already has requests, don't wait */
+       if (!RB_EMPTY_ROOT(&cfqq->sort_list))
+               return false;
+
        /* If there are other queues in the group, don't wait */
        if (cfqq->cfqg->nr_cfqq > 1)
                return false;
 
+       /* the only queue in the group, but think time is big */
+       if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
+               return false;
+
        if (cfq_slice_used(cfqq))
                return true;
 
        /* if slice left is less than think time, wait busy */
-       if (cic && sample_valid(cic->ttime_samples)
-           && (cfqq->slice_end - jiffies < cic->ttime_mean))
+       if (cic && sample_valid(cic->ttime.ttime_samples)
+           && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
                return true;
 
        /*
@@ -3461,11 +3618,24 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
        cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
 
        if (sync) {
-               RQ_CIC(rq)->last_end_request = now;
+               struct cfq_rb_root *service_tree;
+
+               RQ_CIC(rq)->ttime.last_end_request = now;
+
+               if (cfq_cfqq_on_rr(cfqq))
+                       service_tree = cfqq->service_tree;
+               else
+                       service_tree = service_tree_for(cfqq->cfqg,
+                               cfqq_prio(cfqq), cfqq_type(cfqq));
+               service_tree->ttime.last_end_request = now;
                if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
                        cfqd->last_delayed_sync = now;
        }
 
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+       cfqq->cfqg->ttime.last_end_request = now;
+#endif
+
        /*
         * If this is the active queue, check if it needs to be expired,
         * or if we want to idle in case it has no pending requests.
@@ -3511,30 +3681,6 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
                cfq_schedule_dispatch(cfqd);
 }
 
-/*
- * we temporarily boost lower priority queues if they are holding fs exclusive
- * resources. they are boosted to normal prio (CLASS_BE/4)
- */
-static void cfq_prio_boost(struct cfq_queue *cfqq)
-{
-       if (has_fs_excl()) {
-               /*
-                * boost idle prio on transactions that would lock out other
-                * users of the filesystem
-                */
-               if (cfq_class_idle(cfqq))
-                       cfqq->ioprio_class = IOPRIO_CLASS_BE;
-               if (cfqq->ioprio > IOPRIO_NORM)
-                       cfqq->ioprio = IOPRIO_NORM;
-       } else {
-               /*
-                * unboost the queue (if needed)
-                */
-               cfqq->ioprio_class = cfqq->org_ioprio_class;
-               cfqq->ioprio = cfqq->org_ioprio;
-       }
-}
-
 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
 {
        if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
@@ -3565,7 +3711,6 @@ static int cfq_may_queue(struct request_queue *q, int rw)
        cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
        if (cfqq) {
                cfq_init_prio_data(cfqq, cic->ioc);
-               cfq_prio_boost(cfqq);
 
                return __cfq_may_queue(cfqq);
        }
@@ -3588,12 +3733,12 @@ static void cfq_put_request(struct request *rq)
 
                put_io_context(RQ_CIC(rq)->ioc);
 
-               rq->elevator_private = NULL;
-               rq->elevator_private2 = NULL;
+               rq->elevator_private[0] = NULL;
+               rq->elevator_private[1] = NULL;
 
                /* Put down rq reference on cfqg */
                cfq_put_cfqg(RQ_CFQG(rq));
-               rq->elevator_private3 = NULL;
+               rq->elevator_private[2] = NULL;
 
                cfq_put_queue(cfqq);
        }
@@ -3680,19 +3825,15 @@ new_queue:
        }
 
        cfqq->allocated[rw]++;
-       atomic_inc(&cfqq->ref);
 
+       cfqq->ref++;
+       rq->elevator_private[0] = cic;
+       rq->elevator_private[1] = cfqq;
+       rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
        spin_unlock_irqrestore(q->queue_lock, flags);
-
-       rq->elevator_private = cic;
-       rq->elevator_private2 = cfqq;
-       rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
        return 0;
 
 queue_fail:
-       if (cic)
-               put_io_context(cic->ioc);
-
        cfq_schedule_dispatch(cfqd);
        spin_unlock_irqrestore(q->queue_lock, flags);
        cfq_log(cfqd, "set_request fail");
@@ -3787,15 +3928,11 @@ static void cfq_put_async_queues(struct cfq_data *cfqd)
                cfq_put_queue(cfqd->async_idle_cfqq);
 }
 
-static void cfq_cfqd_free(struct rcu_head *head)
-{
-       kfree(container_of(head, struct cfq_data, rcu));
-}
-
 static void cfq_exit_queue(struct elevator_queue *e)
 {
        struct cfq_data *cfqd = e->elevator_data;
        struct request_queue *q = cfqd->queue;
+       bool wait = false;
 
        cfq_shutdown_timer_wq(cfqd);
 
@@ -3814,7 +3951,13 @@ static void cfq_exit_queue(struct elevator_queue *e)
 
        cfq_put_async_queues(cfqd);
        cfq_release_cfq_groups(cfqd);
-       cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
+
+       /*
+        * If there are groups which we could not unlink from blkcg list,
+        * wait for a rcu period for them to be freed.
+        */
+       if (cfqd->nr_blkcg_linked_grps)
+               wait = true;
 
        spin_unlock_irq(q->queue_lock);
 
@@ -3824,8 +3967,25 @@ static void cfq_exit_queue(struct elevator_queue *e)
        ida_remove(&cic_index_ida, cfqd->cic_index);
        spin_unlock(&cic_index_lock);
 
-       /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
-       call_rcu(&cfqd->rcu, cfq_cfqd_free);
+       /*
+        * Wait for cfqg->blkg->key accessors to exit their grace periods.
+        * Do this wait only if there are other unlinked groups out
+        * there. This can happen if cgroup deletion path claimed the
+        * responsibility of cleaning up a group before queue cleanup code
+        * get to the group.
+        *
+        * Do not call synchronize_rcu() unconditionally as there are drivers
+        * which create/delete request queue hundreds of times during scan/boot
+        * and synchronize_rcu() can take significant time and slow down boot.
+        */
+       if (wait)
+               synchronize_rcu();
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+       /* Free up per cpu stats for root group */
+       free_percpu(cfqd->root_group.blkg.stats_cpu);
+#endif
+       kfree(cfqd);
 }
 
 static int cfq_alloc_cic_index(void)
@@ -3858,9 +4018,17 @@ static void *cfq_init_queue(struct request_queue *q)
                return NULL;
 
        cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
-       if (!cfqd)
+       if (!cfqd) {
+               spin_lock(&cic_index_lock);
+               ida_remove(&cic_index_ida, i);
+               spin_unlock(&cic_index_lock);
                return NULL;
+       }
 
+       /*
+        * Don't need take queue_lock in the routine, since we are
+        * initializing the ioscheduler, and nobody is using cfqd
+        */
        cfqd->cic_index = i;
 
        /* Init root service tree */
@@ -3877,14 +4045,34 @@ static void *cfq_init_queue(struct request_queue *q)
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
        /*
-        * Take a reference to root group which we never drop. This is just
-        * to make sure that cfq_put_cfqg() does not try to kfree root group
+        * Set root group reference to 2. One reference will be dropped when
+        * all groups on cfqd->cfqg_list are being deleted during queue exit.
+        * Other reference will remain there as we don't want to delete this
+        * group as it is statically allocated and gets destroyed when
+        * throtl_data goes away.
         */
-       atomic_set(&cfqg->ref, 1);
+       cfqg->ref = 2;
+
+       if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
+               kfree(cfqg);
+
+               spin_lock(&cic_index_lock);
+               ida_remove(&cic_index_ida, cfqd->cic_index);
+               spin_unlock(&cic_index_lock);
+
+               kfree(cfqd);
+               return NULL;
+       }
+
        rcu_read_lock();
+
        cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
                                        (void *)cfqd, 0);
        rcu_read_unlock();
+       cfqd->nr_blkcg_linked_grps++;
+
+       /* Add group on cfqd->cfqg_list */
+       hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
 #endif
        /*
         * Not strictly needed (since RB_ROOT just clears the node and we
@@ -3900,7 +4088,7 @@ static void *cfq_init_queue(struct request_queue *q)
         * will not attempt to free it.
         */
        cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
-       atomic_inc(&cfqd->oom_cfqq.ref);
+       cfqd->oom_cfqq.ref++;
        cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
 
        INIT_LIST_HEAD(&cfqd->cic_list);
@@ -3924,7 +4112,6 @@ static void *cfq_init_queue(struct request_queue *q)
        cfqd->cfq_slice_idle = cfq_slice_idle;
        cfqd->cfq_group_idle = cfq_group_idle;
        cfqd->cfq_latency = 1;
-       cfqd->cfq_group_isolation = 0;
        cfqd->hw_tag = -1;
        /*
         * we optimistically start assuming sync ops weren't delayed in last
@@ -4000,7 +4187,6 @@ SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
-SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
 #undef SHOW_FUNCTION
 
 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                        \
@@ -4034,7 +4220,6 @@ STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
                UINT_MAX, 0);
 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
-STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
 #undef STORE_FUNCTION
 
 #define CFQ_ATTR(name) \
@@ -4052,7 +4237,6 @@ static struct elv_fs_entry cfq_attrs[] = {
        CFQ_ATTR(slice_idle),
        CFQ_ATTR(group_idle),
        CFQ_ATTR(low_latency),
-       CFQ_ATTR(group_isolation),
        __ATTR_NULL
 };
 
@@ -4067,7 +4251,6 @@ static struct elevator_type iosched_cfq = {
                .elevator_add_req_fn =          cfq_insert_request,
                .elevator_activate_req_fn =     cfq_activate_request,
                .elevator_deactivate_req_fn =   cfq_deactivate_request,
-               .elevator_queue_empty_fn =      cfq_queue_empty,
                .elevator_completed_req_fn =    cfq_completed_request,
                .elevator_former_req_fn =       elv_rb_former_request,
                .elevator_latter_req_fn =       elv_rb_latter_request,