[dpdk-dev] [PATCH v4 6/7] power: support monitoring multiple Rx queues

[Anatoly Burakov <anatoly.burakov@intel.com>]

Use the new multi-monitor intrinsic to allow monitoring multiple ethdev
Rx queues while entering the energy efficient power state. The multi
version will be used unconditionally if supported, and the UMWAIT one
will only be used when multi-monitor is not supported by the hardware.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---

Notes:
    v4:
    - Fix possible out of bounds access
    - Added missing index increment

 doc/guides/prog_guide/power_man.rst |  9 ++--
 lib/power/rte_power_pmd_mgmt.c      | 84 ++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 5 deletions(-)

diff --git a/doc/guides/prog_guide/power_man.rst b/doc/guides/prog_guide/power_man.rst
index fac2c19516..3245a5ebed 100644
--- a/doc/guides/prog_guide/power_man.rst
+++ b/doc/guides/prog_guide/power_man.rst
@@ -221,13 +221,16 @@ power saving whenever empty poll count reaches a certain number.
 The "monitor" mode is only supported in the following configurations and scenarios:
 
 * If ``rte_cpu_get_intrinsics_support()`` function indicates that
+  ``rte_power_monitor_multi()`` function is supported by the platform, then
+  monitoring multiple Ethernet Rx queues for traffic will be supported.
+
+* If ``rte_cpu_get_intrinsics_support()`` function indicates that only
   ``rte_power_monitor()`` is supported by the platform, then monitoring will be
   limited to a mapping of 1 core 1 queue (thus, each Rx queue will have to be
   monitored from a different lcore).
 
-* If ``rte_cpu_get_intrinsics_support()`` function indicates that the
-  ``rte_power_monitor()`` function is not supported, then monitor mode will not
-  be supported.
+* If ``rte_cpu_get_intrinsics_support()`` function indicates that neither of the
+  two monitoring functions are supported, then monitor mode will not be supported.
 
 * Not all Ethernet devices support monitoring, even if the underlying
   platform may support the necessary CPU instructions. Please refer to
diff --git a/lib/power/rte_power_pmd_mgmt.c b/lib/power/rte_power_pmd_mgmt.c
index 7762cd39b8..97c9f1ea36 100644
--- a/lib/power/rte_power_pmd_mgmt.c
+++ b/lib/power/rte_power_pmd_mgmt.c
@@ -155,6 +155,32 @@ queue_list_remove(struct pmd_core_cfg *cfg, const union queue *q)
 	return 0;
 }
 
+static inline int
+get_monitor_addresses(struct pmd_core_cfg *cfg,
+		struct rte_power_monitor_cond *pmc, size_t len)
+{
+	const struct queue_list_entry *qle;
+	size_t i = 0;
+	int ret;
+
+	TAILQ_FOREACH(qle, &cfg->head, next) {
+		const union queue *q = &qle->queue;
+		struct rte_power_monitor_cond *cur;
+
+		/* attempted out of bounds access */
+		if (i >= len) {
+			RTE_LOG(ERR, POWER, "Too many queues being monitored\n");
+			return -1;
+		}
+
+		cur = &pmc[i++];
+		ret = rte_eth_get_monitor_addr(q->portid, q->qid, cur);
+		if (ret < 0)
+			return ret;
+	}
+	return 0;
+}
+
 static void
 calc_tsc(void)
 {
@@ -183,6 +209,48 @@ calc_tsc(void)
 	}
 }
 
+static uint16_t
+clb_multiwait(uint16_t port_id, uint16_t qidx,
+		struct rte_mbuf **pkts __rte_unused, uint16_t nb_rx,
+		uint16_t max_pkts __rte_unused, void *addr __rte_unused)
+{
+	const unsigned int lcore = rte_lcore_id();
+	const union queue q = {.portid = port_id, .qid = qidx};
+	const bool empty = nb_rx == 0;
+	struct pmd_core_cfg *q_conf;
+
+	q_conf = &lcore_cfg[lcore];
+
+	/* early exit */
+	if (likely(!empty)) {
+		q_conf->empty_poll_stats = 0;
+	} else {
+		/* do we care about this particular queue? */
+		if (!queue_is_power_save(q_conf, &q))
+			return nb_rx;
+
+		/*
+		 * we can increment unconditionally here because if there were
+		 * non-empty polls in other queues assigned to this core, we
+		 * dropped the counter to zero anyway.
+		 */
+		q_conf->empty_poll_stats++;
+		if (unlikely(q_conf->empty_poll_stats > EMPTYPOLL_MAX)) {
+			struct rte_power_monitor_cond pmc[RTE_MAX_ETHPORTS];
+			uint16_t ret;
+
+			/* gather all monitoring conditions */
+			ret = get_monitor_addresses(q_conf, pmc, RTE_DIM(pmc));
+
+			if (ret == 0)
+				rte_power_monitor_multi(pmc,
+					q_conf->n_queues, UINT64_MAX);
+		}
+	}
+
+	return nb_rx;
+}
+
 static uint16_t
 clb_umwait(uint16_t port_id, uint16_t qidx, struct rte_mbuf **pkts __rte_unused,
 		uint16_t nb_rx, uint16_t max_pkts __rte_unused,
@@ -348,14 +416,19 @@ static int
 check_monitor(struct pmd_core_cfg *cfg, const union queue *qdata)
 {
 	struct rte_power_monitor_cond dummy;
+	bool multimonitor_supported;
 
 	/* check if rte_power_monitor is supported */
 	if (!global_data.intrinsics_support.power_monitor) {
 		RTE_LOG(DEBUG, POWER, "Monitoring intrinsics are not supported\n");
 		return -ENOTSUP;
 	}
+	/* check if multi-monitor is supported */
+	multimonitor_supported =
+			global_data.intrinsics_support.power_monitor_multi;
 
-	if (cfg->n_queues > 0) {
+	/* if we're adding a new queue, do we support multiple queues? */
+	if (cfg->n_queues > 0 && !multimonitor_supported) {
 		RTE_LOG(DEBUG, POWER, "Monitoring multiple queues is not supported\n");
 		return -ENOTSUP;
 	}
@@ -371,6 +444,13 @@ check_monitor(struct pmd_core_cfg *cfg, const union queue *qdata)
 	return 0;
 }
 
+static inline rte_rx_callback_fn
+get_monitor_callback(void)
+{
+	return global_data.intrinsics_support.power_monitor_multi ?
+		clb_multiwait : clb_umwait;
+}
+
 int
 rte_power_ethdev_pmgmt_queue_enable(unsigned int lcore_id, uint16_t port_id,
 		uint16_t queue_id, enum rte_power_pmd_mgmt_type mode)
@@ -434,7 +514,7 @@ rte_power_ethdev_pmgmt_queue_enable(unsigned int lcore_id, uint16_t port_id,
 		if (ret < 0)
 			goto end;
 
-		clb = clb_umwait;
+		clb = get_monitor_callback();
 		break;
 	case RTE_POWER_MGMT_TYPE_SCALE:
 		/* check if we can add a new queue */
-- 
2.25.1