[PATCH] IO Controller: Don't store the pid in single queue circumstances

[Gui Jianfeng <guijianfeng@cn.fujitsu.com>]

Vivek Goyal wrote:
...
> +int elv_init_ioq(struct elevator_queue *eq, struct io_queue *ioq,
> +			void *sched_queue, int ioprio_class, int ioprio,
> +			int is_sync)
> +{
> +	struct elv_fq_data *efqd = &eq->efqd;
> +	struct io_group *iog = io_lookup_io_group_current(efqd->queue);
> +
> +	RB_CLEAR_NODE(&ioq->entity.rb_node);
> +	atomic_set(&ioq->ref, 0);
> +	ioq->efqd = efqd;
> +	ioq->entity.budget = efqd->elv_slice[is_sync];
> +	elv_ioq_set_ioprio_class(ioq, ioprio_class);
> +	elv_ioq_set_ioprio(ioq, ioprio);
> +	ioq->pid = current->pid;

  Hi Vivek,

  Storing a pid in single queue circumstances doesn't make sence.
  So just store the pid when cfq is used.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
 ---
 block/elevator-fq.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index df53418..c72f7e6 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -1988,7 +1988,10 @@ int elv_init_ioq(struct elevator_queue *eq, struct io_queue *ioq,
 	ioq->entity.budget = efqd->elv_slice[is_sync];
 	elv_ioq_set_ioprio_class(ioq, ioprio_class);
 	elv_ioq_set_ioprio(ioq, ioprio);
-	ioq->pid = current->pid;
+	if (elv_iosched_single_ioq(eq))
+		ioq->pid = 0;
+	else
+		ioq->pid = current->pid;
 	ioq->sched_queue = sched_queue;
 
 	/* If generic idle logic is enabled, mark it */
-- 
1.5.4.rc3