[dpdk-dev] [PATCH v3 2/3] event/dsw: make use of eventdev maintenance facility

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

Set the RTE_EVENT_DEV_CAP_REQUIRES_MAINT flag, and perform DSW
background tasks on rte_event_maintain() calls.

PATCH v3:
  - Add support for output buffer flushing by means of the new
    rte_event_maintain() op parameter, and RTE_EVENT_DEV_MAINT_OP_FLUSH.
PATCH v2:
  - Update DSW documentation.
RFC v2:
  - Have dsw_event_maintain() occasionally flush the port output
    buffers.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Tested-by: Richard Eklycke <richard.eklycke@ericsson.com>
Tested-by: Liron Himi <lironh@marvell.com>
---
 doc/guides/eventdevs/dsw.rst  | 27 +++++++++++++++------------
 drivers/event/dsw/dsw_evdev.c |  4 +++-
 drivers/event/dsw/dsw_evdev.h |  1 +
 drivers/event/dsw/dsw_event.c | 12 ++++++++++++
 4 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/doc/guides/eventdevs/dsw.rst b/doc/guides/eventdevs/dsw.rst
index 6653f501c1..18f7e9588f 100644
--- a/doc/guides/eventdevs/dsw.rst
+++ b/doc/guides/eventdevs/dsw.rst
@@ -40,20 +40,20 @@ Example:
 Limitations
 -----------
 
-Unattended Ports
+Port Maintenance
 ~~~~~~~~~~~~~~~~
 
-The distributed software eventdev uses an internal signaling schema
-between the ports to achieve load balancing. In order for this to
-work, the application must perform enqueue and/or dequeue operations
-on all ports.
+The distributed software eventdev uses an internal signaling scheme
+between the ports to achieve load balancing. Therefore, it sets the
+``RTE_EVENT_DEV_CAP_REQUIRES_MAINT`` flag.
 
-Producer-only ports which currently have no events to enqueue should
-periodically call rte_event_enqueue_burst() with a zero-sized burst.
+During periods when the application thread using a particular port is
+neither attempting to enqueue nor to dequeue events, it must
+repeatedly call rte_event_maintain() on that port.
 
-Ports left unattended for longer periods of time will prevent load
-balancing, and also cause traffic interruptions on the flows which
-are in the process of being migrated.
+Ports left unmaintained for long periods of time will prevent load
+balancing and cause traffic interruptions on flows which are in the
+process of being migrated.
 
 Output Buffering
 ~~~~~~~~~~~~~~~~
@@ -66,8 +66,11 @@ In case no more events are enqueued on a port with buffered events,
 these events will be sent after the application has performed a number
 of enqueue and/or dequeue operations.
 
-For explicit flushing, an application may call
-rte_event_enqueue_burst() with a zero-sized burst.
+To immediately flush a port's output buffer, an application may call
+rte_event_maintain() with op set to ``RTE_EVENT_DEV_MAINT_OP_FLUSH``.
+
+Repeated calls to rte_event_maintain() will also flush the output
+buffers.
 
 
 Priorities
diff --git a/drivers/event/dsw/dsw_evdev.c b/drivers/event/dsw/dsw_evdev.c
index 0652d83ad6..5ff8fcc6a9 100644
--- a/drivers/event/dsw/dsw_evdev.c
+++ b/drivers/event/dsw/dsw_evdev.c
@@ -222,7 +222,8 @@ dsw_info_get(struct rte_eventdev *dev __rte_unused,
 		RTE_EVENT_DEV_CAP_DISTRIBUTED_SCHED|
 		RTE_EVENT_DEV_CAP_NONSEQ_MODE|
 		RTE_EVENT_DEV_CAP_MULTIPLE_QUEUE_PORT|
-		RTE_EVENT_DEV_CAP_CARRY_FLOW_ID
+		RTE_EVENT_DEV_CAP_CARRY_FLOW_ID|
+		RTE_EVENT_DEV_CAP_REQUIRES_MAINT
 	};
 }
 
@@ -441,6 +442,7 @@ dsw_probe(struct rte_vdev_device *vdev)
 	dev->enqueue_forward_burst = dsw_event_enqueue_forward_burst;
 	dev->dequeue = dsw_event_dequeue;
 	dev->dequeue_burst = dsw_event_dequeue_burst;
+	dev->maintain = dsw_event_maintain;
 
 	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
 		return 0;
diff --git a/drivers/event/dsw/dsw_evdev.h b/drivers/event/dsw/dsw_evdev.h
index 631daea55c..e64ae26f6e 100644
--- a/drivers/event/dsw/dsw_evdev.h
+++ b/drivers/event/dsw/dsw_evdev.h
@@ -271,6 +271,7 @@ uint16_t dsw_event_enqueue_forward_burst(void *port,
 uint16_t dsw_event_dequeue(void *port, struct rte_event *ev, uint64_t wait);
 uint16_t dsw_event_dequeue_burst(void *port, struct rte_event *events,
 				 uint16_t num, uint64_t wait);
+void dsw_event_maintain(void *port, int op);
 
 int dsw_xstats_get_names(const struct rte_eventdev *dev,
 			 enum rte_event_dev_xstats_mode mode,
diff --git a/drivers/event/dsw/dsw_event.c b/drivers/event/dsw/dsw_event.c
index 1f09816945..c6ed470286 100644
--- a/drivers/event/dsw/dsw_event.c
+++ b/drivers/event/dsw/dsw_event.c
@@ -1400,3 +1400,15 @@ dsw_event_dequeue_burst(void *port, struct rte_event *events, uint16_t num,
 
 	return dequeued;
 }
+
+void dsw_event_maintain(void *port, int op)
+{
+	struct dsw_port *source_port = port;
+	struct dsw_evdev *dsw = source_port->dsw;
+
+	dsw_port_note_op(source_port, 0);
+	dsw_port_bg_process(dsw, source_port);
+
+	if (op & RTE_EVENT_DEV_MAINT_OP_FLUSH)
+		dsw_port_flush_out_buffers(dsw, source_port);
+}
-- 
2.25.1