1 files changed, 24 insertions, 4 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 8427697c5437..501ffdf0399c 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -598,8 +598,8 @@ 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_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
         unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
         if (cfqd->cfq_latency) {
@@ -625,6 +625,14 @@ 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_group_slice(cfqd, cfqq);
+
         cfqq->slice_start = jiffies;
         cfqq->slice_end = jiffies + slice;
         cfqq->allocated_slice = slice;
@@ -1661,8 +1669,11 @@ __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_group_slice(cfqd, cfqq);
+                else
+                        cfqq->slice_resid = cfqq->slice_end - jiffies;
                 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
         }
 
@@ -3284,10 +3295,19 @@ 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.
          */