block cfq: make queue preempt work for queues from different workload

[linux-flexiantxendom0-natty.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 8427697..7bfea53 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3284,10 +3284,19 @@ 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.
         */