cfq-iosched: commenting non-obvious initialization

Added a comment to explain the initialization of last_delayed_sync.

Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 98b15b98b85d7ed3837dc8fc1a663a71b2ee367a..69ecee7f4ad47b8b0f2a9c80bf66a7524130eef9 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3759,6 +3759,10 @@ static void *cfq_init_queue(struct request_queue *q)
        cfqd->cfq_latency = 1;
        cfqd->cfq_group_isolation = 0;
        cfqd->hw_tag = -1;
+       /*
+        * we optimistically start assuming sync ops weren't delayed in last
+        * second, in order to have larger depth for async operations.
+        */
        cfqd->last_delayed_sync = jiffies - HZ;
        INIT_RCU_HEAD(&cfqd->rcu);
        return cfqd;