cfq-iosched: Do not merge queues of BE and IDLE classes
Divyesh Shah [Thu, 25 Mar 2010 14:45:57 +0000 (15:45 +0100)]
Even if they are found to be co-operating.

The prio_trees do not have any IDLE cfqqs on them. cfq_close_cooperator()
is called from cfq_select_queue() and cfq_completed_request(). The latter
ensures that the close cooperator code does not get invoked if the current
cfqq is of class IDLE but the former doesn't seem to have any such checks.
So an IDLE cfqq may get merged with a BE cfqq from the same group which
should be avoided.

Signed-off-by: Divyesh Shah<dpshah@google.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/cfq-iosched.c

index 2f91c53..2c7a0f4 100644 (file)
@@ -1723,6 +1723,8 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
 {
        struct cfq_queue *cfqq;
 
+       if (cfq_class_idle(cur_cfqq))
+               return NULL;
        if (!cfq_cfqq_sync(cur_cfqq))
                return NULL;
        if (CFQQ_SEEKY(cur_cfqq))