On Mon, Jul 17, 2017 at 06:36:23PM -0400, Sinan Kaya wrote:

Code is moving the completion queue doorbell after processing all completed
events and sending callbacks to the block layer on each iteration.

This is causing a performance drop when a lot of jobs are queued towards
the HW. Move the completion queue doorbell on each loop instead and allow new
jobs to be queued by the HW.

That doesn't make sense. Aggregating doorbell writes should be much more
efficient for high depth workloads.