This patch add support for handling urgent requests.
ROW queue can be marked as "urgent" so if it was un-served and a
request was added to it - it will trigger issuing urgent request
to the driver.
Signed-off-by: Tatyana Brokhman <tlinder@xxxxxxxxxxxxxx>
---
block/row-iosched.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 50 insertions(+), 2 deletions(-)
diff --git a/block/row-iosched.c b/block/row-iosched.c
index 9135416..dd2bbfb 100644
--- a/block/row-iosched.c
+++ b/block/row-iosched.c
@@ -27,6 +27,8 @@
#include <linux/blktrace_api.h>
#include <linux/jiffies.h>
+#include "blk.h"
+
/*
* enum row_queue_prio - Priorities of the ROW queues
*
@@ -58,6 +60,17 @@ 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 */
@@ -269,7 +282,13 @@ static void row_add_request(struct request_queue *q,
rqueue->idle_data.idle_trigger_time =
jiffies + msecs_to_jiffies(rd->read_idle.freq);
}
- 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");
}
/*
@@ -289,7 +308,12 @@ static int row_reinsert_req(struct request_queue *q,
struct row_queue *rqueue = RQ_ROWQ(rq);
/* Verify rqueue is legitimate */
- BUG_ON(rqueue != &rd->row_queues[rqueue->prio].rqueue);
+ 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)]++;
@@ -299,6 +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: dispatch 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
@@ -678,6 +725,7 @@ 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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