From 35e0e757537b9239172e35db773dd062727fd612 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 17 Oct 2011 13:56:53 -0400 Subject: target: use a workqueue for I/O completions Instead of abusing the target processing thread for offloading I/O completion in the backends to user context add a new workqueue. This means completions can be processed as fast as available CPU time allows it, including in parallel with other completions and more importantly I/O submission or QUEUE FULL retries. This should give much better performance especially on loaded systems. As a fallout we can merge all the completed states into a single one. On the downside this change complicates lun reset handling a bit by requiring us to cancel a work item only for those states that have it initialized. The alternative would be to either always initialize the work item to a dummy handler, or always use the same handler and do a switch on the state. The long term solution will be a flag that says that the command has an initialized work item, but that's only going to be useful once we have more users. Signed-off-by: Christoph Hellwig Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_tmr.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/target/target_core_tmr.c') diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index 532ce317406a..570b144a1edb 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -255,6 +255,16 @@ static void core_tmr_drain_task_list( atomic_read(&cmd->t_transport_stop), atomic_read(&cmd->t_transport_sent)); + /* + * If the command may be queued onto a workqueue cancel it now. + * + * This is equivalent to removal from the execute queue in the + * loop above, but we do it down here given that + * cancel_work_sync may block. + */ + if (cmd->t_state == TRANSPORT_COMPLETE) + cancel_work_sync(&cmd->work); + spin_lock_irqsave(&cmd->t_state_lock, flags); target_stop_task(task, &flags); -- cgit v1.2.3-55-g7522