[PATCH] cfq-iosched: check busy queues before deciding we are idle

[linux-2.6] / block / elevator.c

diff --git a/block/elevator.c b/block/elevator.c
index 29825792cbd5305cfbea9c1f6063710ec4b46be8..8768a367fdded922a17b1c7c47ac24ec993a1628 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -333,6 +333,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
 {
        struct list_head *pos;
        unsigned ordseq;
+       int unplug_it = 1;
 
        blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 
@@ -399,6 +400,11 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                }
 
                list_add_tail(&rq->queuelist, pos);
+               /*
+                * most requeues happen because of a busy condition, don't
+                * force unplug of the queue for that case.
+                */
+               unplug_it = 0;
                break;
 
        default:
@@ -407,7 +413,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                BUG();
        }
 
-       if (blk_queue_plugged(q)) {
+       if (unplug_it && blk_queue_plugged(q)) {
                int nrq = q->rq.count[READ] + q->rq.count[WRITE]
                        - q->in_flight;