Corrado Zoccolo e4a229196a cfq-iosched: fix no-idle preemption logic
An incoming no-idle queue should preempt the active no-idle queue
 only if the active queue is idling due to service tree empty.
 Previous code was buggy in two ways:
 * it relied on service_tree field to be set on the active queue, while
   it is not set when the code is idling for a new request
 * it didn't check for the service tree empty condition, so could lead to
   LIFO behaviour if multiple queues with depth > 1 were preempting each
   other on an non-NCQ device.

Reported-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-11-26 10:39:31 +01:00
..
2009-11-11 13:47:45 +01:00
2009-11-10 11:50:21 +01:00
2009-11-11 13:47:45 +01:00
2009-10-03 20:52:01 +02:00
2009-11-10 11:50:21 +01:00
2009-10-03 20:52:01 +02:00