[PATCH v3 0/2] block:row: Adding support for urgent requests handling

[PATCH v3 0/2] block:row: Adding support for urgent requests handling

[Tanya Brokhman]

This patch set add support for handling urgent requests by the
ROW algorith. It depends on 2 previosly uploaded patch sets:
1. ROW scheduling Algorithm
2. Adding support for urgent requests handling (in block layer)

Tanya Brokhman (2):
  row: Adding support for reinsert already dispatched req
  row: Add support for urgent request handling

 block/row-iosched.c |   76 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 75 insertions(+), 1 deletions(-)

-- 
1.7.6
--
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. 
Is a member of Code Aurora Forum, hosted by the Linux Foundation

[PATCH v3 1/2] row: Adding support for reinsert already dispatched req

[Tanya Brokhman]

Add support for reinserting already dispatched request back to the
schedulers internal data structures.
The request will be reinserted back to the queue (head) it was
dispatched from as if it was never dispatched.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
---
v3: Update error handling when row queue is not set for a request  
v2: Nothing changed. Resend
v1: Initial version

diff --git a/block/row-iosched.c b/block/row-iosched.c
index 1f50180..b3204d6 100644
--- a/block/row-iosched.c
+++ b/block/row-iosched.c
@@ -274,7 +274,39 @@ static void row_add_request(struct request_queue *q,
 	row_log_rowq(rd, rqueue->prio, "added request");
 }
 
-/*
+/**
+ * row_reinsert_req() - Reinsert request back to the scheduler
+ * @q:	requests queue
+ * @rq:	request to add
+ *
+ * Reinsert the given request back to the queue it was
+ * dispatched from as if it was never dispatched.
+ *
+ * Returns 0 on success, error code otherwise
+ */
+static int row_reinsert_req(struct request_queue *q,
+			    struct request *rq)
+{
+	struct row_data    *rd = q->elevator->elevator_data;
+	struct row_queue   *rqueue = RQ_ROWQ(rq);
+
+	/* Verify rqueue is legitimate */
+	if (rqueue->prio >= ROWQ_MAX_PRIO) {
+		pr_err("\n\nROW BUG: row_reinsert_req() rqueue->prio = %d\n",
+			   rqueue->prio);
+		blk_dump_rq_flags(rq, "");
+		return -EIO;
+	}
+
+	list_add(&rq->queuelist, &rqueue->fifo);
+	rd->nr_reqs[rq_data_dir(rq)]++;
+
+	row_log_rowq(rd, rqueue->prio, "request reinserted");
+
+	return 0;
+}
+
+/**
  * row_remove_request() -  Remove given request from scheduler
  * @q:	requests queue
  * @rq:	request to remove
@@ -664,6 +696,7 @@ static struct elevator_type iosched_row = {
 		.elevator_merge_req_fn		= row_merged_requests,
 		.elevator_dispatch_fn		= row_dispatch_requests,
 		.elevator_add_req_fn		= row_add_request,
+		.elevator_reinsert_req_fn	= row_reinsert_req,
 		.elevator_former_req_fn		= elv_rb_former_request,
 		.elevator_latter_req_fn		= elv_rb_latter_request,
 		.elevator_set_req_fn		= row_set_request,
-- 
1.7.6
--
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. 
Is a member of Code Aurora Forum, hosted by the Linux Foundation

[PATCH/RESEND v3 2/2] row: Add support for urgent request handling

[Tanya Brokhman]

This patch add support for handling urgent requests.
ROW queue can be marked as "urgent". If an urgent queue was
un-served in a previous dispatch cycle and a request was added
to it - it will trigger issuing urgent request to the device driver.

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

diff --git a/block/row-iosched.c b/block/row-iosched.c
index b3204d6..41cc028 100644
--- a/block/row-iosched.c
+++ b/block/row-iosched.c
@@ -58,6 +58,17 @@ static const bool queue_idling_enabled[] = {
 	false,	/* ROWQ_PRIO_LOW_SWRITE */
 };
 
+/* Flags indicating whether the queue can notify on urgent requests */
+static const bool urgent_queues[] = {
+	true,	/* ROWQ_PRIO_HIGH_READ */
+	true,	/* ROWQ_PRIO_REG_READ */
+	false,	/* ROWQ_PRIO_HIGH_SWRITE */
+	false,	/* ROWQ_PRIO_REG_SWRITE */
+	false,	/* ROWQ_PRIO_REG_WRITE */
+	false,	/* ROWQ_PRIO_LOW_READ */
+	false,	/* ROWQ_PRIO_LOW_SWRITE */
+};
+
 /* Default values for row queues quantums in each dispatch cycle */
 static const int queue_quantum[] = {
 	100,	/* ROWQ_PRIO_HIGH_READ */
@@ -271,7 +282,13 @@ static void row_add_request(struct request_queue *q,
 
 		rqueue->idle_data.last_insert_time = ktime_get();
 	}
-	row_log_rowq(rd, rqueue->prio, "added request");
+	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);
+	} else
+		row_log_rowq(rd, rqueue->prio, "added request");
 }
 
 /**
@@ -306,6 +323,29 @@ static int row_reinsert_req(struct request_queue *q,
 	return 0;
 }
 
+/*
+ * row_urgent_pending() - Return TRUE if there is an urgent
+ *			  request on scheduler
+ * @q:	requests queue
+ *
+ */
+static bool row_urgent_pending(struct request_queue *q)
+{
+	struct row_data *rd = q->elevator->elevator_data;
+	int i;
+
+	for (i = 0; i < ROWQ_MAX_PRIO; i++)
+		if (urgent_queues[i] && row_rowq_unserved(rd, i) &&
+		    !list_empty(&rd->row_queues[i].rqueue.fifo)) {
+			row_log_rowq(rd, i,
+				     "Urgent request pending (curr=%i)",
+				     rd->curr_queue);
+			return true;
+		}
+
+	return false;
+}
+
 /**
  * row_remove_request() -  Remove given request from scheduler
  * @q:	requests queue
@@ -697,6 +737,7 @@ static struct elevator_type iosched_row = {
 		.elevator_dispatch_fn		= row_dispatch_requests,
 		.elevator_add_req_fn		= row_add_request,
 		.elevator_reinsert_req_fn	= row_reinsert_req,
+		.elevator_is_urgent_fn		= row_urgent_pending,
 		.elevator_former_req_fn		= elv_rb_former_request,
 		.elevator_latter_req_fn		= elv_rb_latter_request,
 		.elevator_set_req_fn		= row_set_request,
-- 
1.7.6
--
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. 
Is a member of Code Aurora Forum, hosted by the Linux Foundation