cfq-iosched: temporarily boost queue priority for idle classes

[cascardo/linux.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4e59784..d227ad6 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -141,7 +141,7 @@ struct cfq_queue {
 
        /* io prio of this group */
        unsigned short ioprio, org_ioprio;
-       unsigned short ioprio_class;
+       unsigned short ioprio_class, org_ioprio_class;
 
        pid_t pid;
 
@@ -3700,6 +3700,7 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
         * elevate the priority of this queue
         */
        cfqq->org_ioprio = cfqq->ioprio;
+       cfqq->org_ioprio_class = cfqq->ioprio_class;
        cfq_clear_cfqq_prio_changed(cfqq);
 }
 
@@ -4295,6 +4296,24 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
                cfq_schedule_dispatch(cfqd);
 }
 
+static void cfqq_boost_on_prio(struct cfq_queue *cfqq, int op_flags)
+{
+       /*
+        * If REQ_PRIO is set, boost class and prio level, if it's below
+        * BE/NORM. If prio is not set, restore the potentially boosted
+        * class/prio level.
+        */
+       if (!(op_flags & REQ_PRIO)) {
+               cfqq->ioprio_class = cfqq->org_ioprio_class;
+               cfqq->ioprio = cfqq->org_ioprio;
+       } else {
+               if (cfq_class_idle(cfqq))
+                       cfqq->ioprio_class = IOPRIO_CLASS_BE;
+               if (cfqq->ioprio > IOPRIO_NORM)
+                       cfqq->ioprio = IOPRIO_NORM;
+       }
+}
+
 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
 {
        if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
@@ -4325,6 +4344,7 @@ static int cfq_may_queue(struct request_queue *q, int op, int op_flags)
        cfqq = cic_to_cfqq(cic, rw_is_sync(op, op_flags));
        if (cfqq) {
                cfq_init_prio_data(cfqq, cic);
+               cfqq_boost_on_prio(cfqq, op_flags);
 
                return __cfq_may_queue(cfqq);
        }