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>

1 files changed, 4 insertions, 0 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 98b15b98b85d..69ecee7f4ad4 100644
--- 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;