cfq-iosched: Don't group_idle if cfqq has big thinktime

There is no point in idling on a cfq group if the only cfq queue that is
there has too big thinktime.

Signed-off-by: Jan Kara <jack@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1f9093e901daed7849a54633be5d80ce96b010f4..0a6a70a9bca858ad17924b72a336a65ff335031b 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2897,6 +2897,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq = cfqd->active_queue;
+       struct cfq_rb_root *st = cfqq->service_tree;
        struct cfq_io_cq *cic;
        unsigned long sl, group_idle = 0;
 
@@ -2947,8 +2948,13 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
                return;
        }
 
-       /* There are other queues in the group, don't do group idle */
-       if (group_idle && cfqq->cfqg->nr_cfqq > 1)
+       /*
+        * There are other queues in the group or this is the only group and
+        * it has too big thinktime, don't do group idle.
+        */
+       if (group_idle &&
+           (cfqq->cfqg->nr_cfqq > 1 ||
+            cfq_io_thinktime_big(cfqd, &st->ttime, true)))
                return;
 
        cfq_mark_cfqq_wait_request(cfqq);