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@xxxxxxxxxxxxxx>
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
--
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