block: row: Add some debug information on ROW queues

1. Add a counter for number of requests on queue.
2. Add function to print queues status (number requests
   currently on queue and number of already dispatched requests
   in current dispatch cycle).

Change-Id: I1e98b9ca33853e6e6a8ddc53240f6cd6981e6024
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>

block/row-iosched.c

@@ -1,7 +1,7 @@
 /*
  * ROW (Read Over Write) I/O scheduler.
  *
- * Copyright (c) 2012, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -104,6 +104,7 @@ struct rowq_idling_data {
  * @nr_dispatched:	number of requests already dispatched in
  *			the current dispatch cycle
  * @slice:		number of requests to dispatch in a cycle
+ * @nr_req:		number of requests in queue
  * @idle_data:		data for idling on queues
  *
  */
@@ -115,6 +116,8 @@ struct row_queue {
 	unsigned int		nr_dispatched;
 	unsigned int		slice;
 
+	unsigned int		nr_req;
+
 	/* used only for READ queues */
 	struct rowq_idling_data	idle_data;
 };
@@ -191,6 +194,19 @@ static inline int row_rowq_unserved(struct row_data *rd,
 	return rd->cycle_flags & (1 << qnum);
 }
 
+static inline void __maybe_unused row_dump_queues_stat(struct row_data *rd)
+{
+	int i;
+
+	row_log(rd->dispatch_queue, " Queues status (curr_queue=%d):",
+			rd->curr_queue);
+	for (i = 0; i < ROWQ_MAX_PRIO; i++)
+		row_log(rd->dispatch_queue,
+			"queue%d: dispatched= %d, nr_req=%d", i,
+			rd->row_queues[i].nr_dispatched,
+			rd->row_queues[i].nr_req);
+}
+
 /******************** Static helper functions ***********************/
 /*
  * kick_queue() - Wake up device driver queue thread
@@ -264,6 +280,7 @@ static void row_add_request(struct request_queue *q,
 
 	list_add_tail(&rq->queuelist, &rqueue->fifo);
 	rd->nr_reqs[rq_data_dir(rq)]++;
+	rqueue->nr_req++;
 	rq_set_fifo_time(rq, jiffies); /* for statistics*/
 
 	if (queue_idling_enabled[rqueue->prio]) {
@@ -285,10 +302,11 @@ static void row_add_request(struct request_queue *q,
 	if (urgent_queues[rqueue->prio] &&
 	    row_rowq_unserved(rd, rqueue->prio)) {
 		row_log_rowq(rd, rqueue->prio,
-			     "added urgent req curr_queue = %d",
-			     rd->curr_queue);
+			"added urgent request (total on queue=%d)",
+			rqueue->nr_req);
 	} else
-		row_log_rowq(rd, rqueue->prio, "added request");
+		row_log_rowq(rd, rqueue->prio,
+			"added request (total on queue=%d)", rqueue->nr_req);
 }
 
 /**
@@ -317,8 +335,10 @@ static int row_reinsert_req(struct request_queue *q,
 
 	list_add(&rq->queuelist, &rqueue->fifo);
 	rd->nr_reqs[rq_data_dir(rq)]++;
+	rqueue->nr_req++;
 
-	row_log_rowq(rd, rqueue->prio, "request reinserted");
+	row_log_rowq(rd, rqueue->prio,
+		"request reinserted (total on queue=%d)", rqueue->nr_req);
 
 	return 0;
 }
@@ -355,8 +375,10 @@ static void row_remove_request(struct request_queue *q,
 			       struct request *rq)
 {
 	struct row_data *rd = (struct row_data *)q->elevator->elevator_data;
+	struct row_queue *rqueue = RQ_ROWQ(rq);
 
 	rq_fifo_clear(rq);
+	rqueue->nr_req--;
 	rd->nr_reqs[rq_data_dir(rq)]--;
 }
 
@@ -438,7 +460,8 @@ static int row_dispatch_requests(struct request_queue *q, int force)
 		if (row_rowq_unserved(rd, i) &&
 		    !list_empty(&rd->row_queues[i].rqueue.fifo)) {
 			row_log_rowq(rd, currq,
-				" Preemting for unserved rowq%d", i);
+				" Preemting for unserved rowq%d. (nr_req=%u)",
+				i, rd->row_queues[currq].rqueue.nr_req);
 			rd->curr_queue = i;
 			row_dispatch_insert(rd);
 			ret = 1;
@@ -583,6 +606,7 @@ static void row_merged_requests(struct request_queue *q, struct request *rq,
 	struct row_queue   *rqueue = RQ_ROWQ(next);
 
 	list_del_init(&next->queuelist);
+	rqueue->nr_req--;
 
 	rqueue->rdata->nr_reqs[rq_data_dir(rq)]--;
 }