cfq-iosched: Respect ioprio_class when preempting
[linux-2.6.git] / block / cfq-iosched.c
index 69ecee7..ee130f1 100644 (file)
@@ -208,8 +208,6 @@ struct cfq_data {
        /* Root service tree for cfq_groups */
        struct cfq_rb_root grp_service_tree;
        struct cfq_group root_group;
-       /* Number of active cfq groups on group service tree */
-       int nr_groups;
 
        /*
         * The priority currently being served
@@ -294,8 +292,7 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
 
 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
                                            enum wl_prio_t prio,
-                                           enum wl_type_t type,
-                                           struct cfq_data *cfqd)
+                                           enum wl_type_t type)
 {
        if (!cfqg)
                return NULL;
@@ -842,7 +839,6 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
 
        __cfq_group_service_tree_add(st, cfqg);
        cfqg->on_st = true;
-       cfqd->nr_groups++;
        st->total_weight += cfqg->weight;
 }
 
@@ -863,7 +859,6 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
 
        cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
        cfqg->on_st = false;
-       cfqd->nr_groups--;
        st->total_weight -= cfqg->weight;
        if (!RB_EMPTY_NODE(&cfqg->rb_node))
                cfq_rb_erase(&cfqg->rb_node, st);
@@ -1150,7 +1145,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 #endif
 
        service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
-                                               cfqq_type(cfqq), cfqd);
+                                               cfqq_type(cfqq));
        if (cfq_class_idle(cfqq)) {
                rb_key = CFQ_IDLE_DELAY;
                parent = rb_last(&service_tree->rb);
@@ -1513,9 +1508,6 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
        struct cfq_io_context *cic;
        struct cfq_queue *cfqq;
 
-       /* Deny merge if bio and rq don't belong to same cfq group */
-       if ((RQ_CFQQ(rq))->cfqg != cfq_get_cfqg(cfqd, 0))
-               return false;
        /*
         * Disallow merge of a sync bio into an async request.
         */
@@ -1616,7 +1608,7 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
 {
        struct cfq_rb_root *service_tree =
                service_tree_for(cfqd->serving_group, cfqd->serving_prio,
-                                       cfqd->serving_type, cfqd);
+                                       cfqd->serving_type);
 
        if (!cfqd->rq_queued)
                return NULL;
@@ -1675,13 +1667,17 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
 #define CFQQ_SEEKY(cfqq)       ((cfqq)->seek_mean > CFQQ_SEEK_THR)
 
 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-                              struct request *rq)
+                              struct request *rq, bool for_preempt)
 {
        sector_t sdist = cfqq->seek_mean;
 
        if (!sample_valid(cfqq->seek_samples))
                sdist = CFQQ_SEEK_THR;
 
+       /* if seek_mean is big, using it as close criteria is meaningless */
+       if (sdist > CFQQ_SEEK_THR && !for_preempt)
+               sdist = CFQQ_SEEK_THR;
+
        return cfq_dist_from_last(cfqd, rq) <= sdist;
 }
 
@@ -1709,7 +1705,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
         * will contain the closest sector.
         */
        __cfqq = rb_entry(parent, struct cfq_queue, p_node);
-       if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
+       if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false))
                return __cfqq;
 
        if (blk_rq_pos(__cfqq->next_rq) < sector)
@@ -1720,7 +1716,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
                return NULL;
 
        __cfqq = rb_entry(node, struct cfq_queue, p_node);
-       if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
+       if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false))
                return __cfqq;
 
        return NULL;
@@ -1963,8 +1959,7 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
 }
 
 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
-                               struct cfq_group *cfqg, enum wl_prio_t prio,
-                               bool prio_changed)
+                               struct cfq_group *cfqg, enum wl_prio_t prio)
 {
        struct cfq_queue *queue;
        int i;
@@ -1972,24 +1967,9 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
        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(cfqg, prio, cur_best, cfqd)->count)
-                       return cur_best;
-               cur_best = SYNC_WORKLOAD;
-               if (service_tree_for(cfqg, 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(cfqg, prio, i, cfqd));
+       for (i = 0; i <= SYNC_WORKLOAD; ++i) {
+               /* select the one with lowest rb_key */
+               queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
                if (queue &&
                    (!key_valid || time_before(queue->rb_key, lowest_key))) {
                        lowest_key = queue->rb_key;
@@ -2003,8 +1983,6 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
 
 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
 {
-       enum wl_prio_t previous_prio = cfqd->serving_prio;
-       bool prio_changed;
        unsigned slice;
        unsigned count;
        struct cfq_rb_root *st;
@@ -2032,24 +2010,19 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
         * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
         * expiration time
         */
-       prio_changed = (cfqd->serving_prio != previous_prio);
-       st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
-                               cfqd);
+       st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
        count = st->count;
 
        /*
-        * If priority didn't change, check workload expiration,
-        * and that we still have other queues ready
+        * check workload expiration, and that we still have other queues ready
         */
-       if (!prio_changed && count &&
-           !time_after(jiffies, cfqd->workload_expires))
+       if (count && !time_after(jiffies, cfqd->workload_expires))
                return;
 
        /* otherwise select new workload type */
        cfqd->serving_type =
-               cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio, prio_changed);
-       st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
-                               cfqd);
+               cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
+       st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
        count = st->count;
 
        /*
@@ -2113,7 +2086,9 @@ static void cfq_choose_cfqg(struct cfq_data *cfqd)
                cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
                cfqd->serving_type = cfqg->saved_workload;
                cfqd->serving_prio = cfqg->saved_serving_prio;
-       }
+       } else
+               cfqd->workload_expires = jiffies - 1;
+
        choose_service_tree(cfqd, cfqg);
 }
 
@@ -2151,10 +2126,11 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
                 * have been idling all along on this queue and it should be
                 * ok to wait for this request to complete.
                 */
-               if (cfqq->cfqg->nr_cfqq == 1 && cfqq->dispatched
-                   && cfq_should_idle(cfqd, cfqq))
+               if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
+                   && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
+                       cfqq = NULL;
                        goto keep_queue;
-               else
+               } else
                        goto expire;
        }
 
@@ -3101,6 +3077,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
                return true;
 
        /*
+        * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
+        */
+       if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
+               return false;
+
+       /*
         * if the new request is sync, but the currently running queue is
         * not, let the sync request have priority.
         */
@@ -3140,7 +3122,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
         * if this request is as-good as one we would expect from the
         * current cfqq, let it preempt
         */
-       if (cfq_rq_close(cfqd, cfqq, rq))
+       if (cfq_rq_close(cfqd, cfqq, rq, true))
                return true;
 
        return false;
@@ -3202,6 +3184,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                        if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
                            cfqd->busy_queues > 1) {
                                del_timer(&cfqd->idle_slice_timer);
+                               cfq_clear_cfqq_wait_request(cfqq);
                                __blk_run_queue(cfqd->queue);
                        } else
                                cfq_mark_cfqq_must_dispatch(cfqq);