Re: [dpdk-dev] [RFC PATCH v1 4/6] app/eventdev: add release barriers for pipeline test

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

>Add release barriers before updating the processed packets for worker
>lcores to ensure the worker lcore has really finished data processing
>and then it can update the processed packets number.
>

I believe we can live with minor inaccuracies in stats being presented
as atomics are pretty heavy when scheduler is limited to burst size as 1. 

One option is to move it before a pipeline operation (pipeline_event_tx, pipeline_fwd_event etc.)
as they imply implicit release barrier (as all the changes done to the event should be visible to the next core).

>Fixes: 314bcf58ca8f ("app/eventdev: add pipeline queue worker
>functions")
>Cc: pbhagavatula@marvell.com
>Cc: stable@dpdk.org
>
>Signed-off-by: Phil Yang <phil.yang@arm.com>
>Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
>Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
>---
> app/test-eventdev/test_pipeline_queue.c | 64
>+++++++++++++++++++++----
> 1 file changed, 56 insertions(+), 8 deletions(-)
>
>diff --git a/app/test-eventdev/test_pipeline_queue.c b/app/test-
>eventdev/test_pipeline_queue.c
>index 7bebac34f..0c0ec0ceb 100644
>--- a/app/test-eventdev/test_pipeline_queue.c
>+++ b/app/test-eventdev/test_pipeline_queue.c
>@@ -30,7 +30,13 @@ pipeline_queue_worker_single_stage_tx(void
>*arg)
>
> 		if (ev.sched_type == RTE_SCHED_TYPE_ATOMIC) {
> 			pipeline_event_tx(dev, port, &ev);
>-			w->processed_pkts++;
>+
>+			/* release barrier here ensures stored operation
>+			 * of the event completes before the number of
>+			 * processed pkts is visible to the main core
>+			 */
>+			__atomic_fetch_add(&(w->processed_pkts), 1,
>+					__ATOMIC_RELEASE);
> 		} else {
> 			ev.queue_id++;
> 			pipeline_fwd_event(&ev,
>RTE_SCHED_TYPE_ATOMIC);
>@@ -59,7 +65,13 @@ pipeline_queue_worker_single_stage_fwd(void
>*arg)
> 		rte_event_eth_tx_adapter_txq_set(ev.mbuf, 0);
> 		pipeline_fwd_event(&ev, RTE_SCHED_TYPE_ATOMIC);
> 		pipeline_event_enqueue(dev, port, &ev);
>-		w->processed_pkts++;
>+
>+		/* release barrier here ensures stored operation
>+		 * of the event completes before the number of
>+		 * processed pkts is visible to the main core
>+		 */
>+		__atomic_fetch_add(&(w->processed_pkts), 1,
>+				__ATOMIC_RELEASE);
> 	}
>
> 	return 0;
>@@ -84,7 +96,13 @@
>pipeline_queue_worker_single_stage_burst_tx(void *arg)
> 			if (ev[i].sched_type ==
>RTE_SCHED_TYPE_ATOMIC) {
> 				pipeline_event_tx(dev, port, &ev[i]);
> 				ev[i].op = RTE_EVENT_OP_RELEASE;
>-				w->processed_pkts++;
>+
>+				/* release barrier here ensures stored
>operation
>+				 * of the event completes before the
>number of
>+				 * processed pkts is visible to the main
>core
>+				 */
>+				__atomic_fetch_add(&(w-
>>processed_pkts), 1,
>+						__ATOMIC_RELEASE);
> 			} else {
> 				ev[i].queue_id++;
> 				pipeline_fwd_event(&ev[i],
>@@ -121,7 +139,13 @@
>pipeline_queue_worker_single_stage_burst_fwd(void *arg)
> 		}
>
> 		pipeline_event_enqueue_burst(dev, port, ev, nb_rx);
>-		w->processed_pkts += nb_rx;
>+
>+		/* release barrier here ensures stored operation
>+		 * of the event completes before the number of
>+		 * processed pkts is visible to the main core
>+		 */
>+		__atomic_fetch_add(&(w->processed_pkts), nb_rx,
>+				__ATOMIC_RELEASE);
> 	}
>
> 	return 0;
>@@ -146,7 +170,13 @@ pipeline_queue_worker_multi_stage_tx(void
>*arg)
>
> 		if (ev.queue_id == tx_queue[ev.mbuf->port]) {
> 			pipeline_event_tx(dev, port, &ev);
>-			w->processed_pkts++;
>+
>+			/* release barrier here ensures stored operation
>+			 * of the event completes before the number of
>+			 * processed pkts is visible to the main core
>+			 */
>+			__atomic_fetch_add(&(w->processed_pkts), 1,
>+					__ATOMIC_RELEASE);
> 			continue;
> 		}
>
>@@ -180,7 +210,13 @@
>pipeline_queue_worker_multi_stage_fwd(void *arg)
> 			ev.queue_id = tx_queue[ev.mbuf->port];
> 			rte_event_eth_tx_adapter_txq_set(ev.mbuf, 0);
> 			pipeline_fwd_event(&ev,
>RTE_SCHED_TYPE_ATOMIC);
>-			w->processed_pkts++;
>+
>+			/* release barrier here ensures stored operation
>+			 * of the event completes before the number of
>+			 * processed pkts is visible to the main core
>+			 */
>+			__atomic_fetch_add(&(w->processed_pkts), 1,
>+					__ATOMIC_RELEASE);
> 		} else {
> 			ev.queue_id++;
> 			pipeline_fwd_event(&ev,
>sched_type_list[cq_id]);
>@@ -214,7 +250,13 @@
>pipeline_queue_worker_multi_stage_burst_tx(void *arg)
> 			if (ev[i].queue_id == tx_queue[ev[i].mbuf-
>>port]) {
> 				pipeline_event_tx(dev, port, &ev[i]);
> 				ev[i].op = RTE_EVENT_OP_RELEASE;
>-				w->processed_pkts++;
>+
>+				/* release barrier here ensures stored
>operation
>+				 * of the event completes before the
>number of
>+				 * processed pkts is visible to the main
>core
>+				 */
>+				__atomic_fetch_add(&(w-
>>processed_pkts), 1,
>+						__ATOMIC_RELEASE);
> 				continue;
> 			}
>
>@@ -254,7 +296,13 @@
>pipeline_queue_worker_multi_stage_burst_fwd(void *arg)
>
>	rte_event_eth_tx_adapter_txq_set(ev[i].mbuf, 0);
> 				pipeline_fwd_event(&ev[i],
>
>	RTE_SCHED_TYPE_ATOMIC);
>-				w->processed_pkts++;
>+
>+				/* release barrier here ensures stored
>operation
>+				 * of the event completes before the
>number of
>+				 * processed pkts is visible to the main
>core
>+				 */
>+				__atomic_fetch_add(&(w-
>>processed_pkts), 1,
>+						__ATOMIC_RELEASE);
> 			} else {
> 				ev[i].queue_id++;
> 				pipeline_fwd_event(&ev[i],
>--
>2.17.1