[dpdk-dev] [PATCH v2 2/3] event/sw: implement unlinks in progress function

[Harry van Haaren <harry.van.haaren@intel.com>]

This commit adds a counter to each port, which counts the
number of unlinks that have been performed. When the scheduler
thread starts its scheduling routine, it "acks" all unlinks that
have been requested, and the application is gauranteed that no
more events will be scheduled to the port from the unlinked queue.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>

---

v2:
- Fix unused "dev" variable (Jerin)
---
 drivers/event/sw/sw_evdev.c           | 12 ++++++++++++
 drivers/event/sw/sw_evdev.h           |  8 ++++++++
 drivers/event/sw/sw_evdev_scheduler.c |  7 ++++++-
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/event/sw/sw_evdev.c b/drivers/event/sw/sw_evdev.c
index a6bb91388..9e1412537 100644
--- a/drivers/event/sw/sw_evdev.c
+++ b/drivers/event/sw/sw_evdev.c
@@ -113,9 +113,20 @@ sw_port_unlink(struct rte_eventdev *dev, void *port, uint8_t queues[],
 			}
 		}
 	}
+
+	p->unlinks_in_progress += unlinked;
+	rte_smp_mb();
+
 	return unlinked;
 }
 
+static int
+sw_port_unlinks_in_progress(struct rte_eventdev *dev, void *port)
+{
+	struct sw_port *p = port;
+	return p->unlinks_in_progress;
+}
+
 static int
 sw_port_setup(struct rte_eventdev *dev, uint8_t port_id,
 		const struct rte_event_port_conf *conf)
@@ -925,6 +936,7 @@ sw_probe(struct rte_vdev_device *vdev)
 			.port_release = sw_port_release,
 			.port_link = sw_port_link,
 			.port_unlink = sw_port_unlink,
+			.port_unlinks_in_progress = sw_port_unlinks_in_progress,
 
 			.eth_rx_adapter_caps_get = sw_eth_rx_adapter_caps_get,
 
diff --git a/drivers/event/sw/sw_evdev.h b/drivers/event/sw/sw_evdev.h
index d90b96d4b..7c77b2495 100644
--- a/drivers/event/sw/sw_evdev.h
+++ b/drivers/event/sw/sw_evdev.h
@@ -148,6 +148,14 @@ struct sw_port {
 	/* A numeric ID for the port */
 	uint8_t id;
 
+	/* An atomic counter for when the port has been unlinked, and the
+	 * scheduler has not yet acked this unlink - hence there may still be
+	 * events in the buffers going to the port. When the unlinks in
+	 * progress is read by the scheduler, no more events will be pushed to
+	 * the port - hence the scheduler core can just assign zero.
+	 */
+	uint8_t unlinks_in_progress;
+
 	int16_t is_directed; /** Takes from a single directed QID */
 	/**
 	 * For loadbalanced we can optimise pulling packets from
diff --git a/drivers/event/sw/sw_evdev_scheduler.c b/drivers/event/sw/sw_evdev_scheduler.c
index e3a41e02f..9b54d5ce7 100644
--- a/drivers/event/sw/sw_evdev_scheduler.c
+++ b/drivers/event/sw/sw_evdev_scheduler.c
@@ -517,13 +517,18 @@ sw_event_schedule(struct rte_eventdev *dev)
 		/* Pull from rx_ring for ports */
 		do {
 			in_pkts = 0;
-			for (i = 0; i < sw->port_count; i++)
+			for (i = 0; i < sw->port_count; i++) {
+				/* ack the unlinks in progress as done */
+				if (sw->ports[i].unlinks_in_progress)
+					sw->ports[i].unlinks_in_progress = 0;
+
 				if (sw->ports[i].is_directed)
 					in_pkts += sw_schedule_pull_port_dir(sw, i);
 				else if (sw->ports[i].num_ordered_qids > 0)
 					in_pkts += sw_schedule_pull_port_lb(sw, i);
 				else
 					in_pkts += sw_schedule_pull_port_no_reorder(sw, i);
+			}
 
 			/* QID scan for re-ordered */
 			in_pkts += sw_schedule_reorder(sw, 0,
-- 
2.17.1