[dpdk-dev] [PATCH v3 21/30] net/ena: add Tx drops statistic

[Michal Krawczyk <mk@semihalf.com>]

ENA device can report in the AENQ handler amount of Tx packets that were
dropped and not sent.

This statistic is showing global value for the device and because
rte_eth_stats is missing field that could indicate this value (it
isn't the Tx error), it is being presented as a extended statistic.

As the current design of extended statistics prevents tx_drops from
being an atomic variable and both tx_drops and rx_drops are only updated
from the AENQ handler, both were set as non-atomic for the alignment.

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Guy Tzalik <gtzalik@amazon.com>
---
v3:
  * Update release notes

 doc/guides/rel_notes/release_20_05.rst |  1 +
 drivers/net/ena/ena_ethdev.c           | 11 ++++++++---
 drivers/net/ena/ena_ethdev.h           |  8 +++++++-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/doc/guides/rel_notes/release_20_05.rst b/doc/guides/rel_notes/release_20_05.rst
index 7c73fe8fd5..bcd8d86299 100644
--- a/doc/guides/rel_notes/release_20_05.rst
+++ b/doc/guides/rel_notes/release_20_05.rst
@@ -83,6 +83,7 @@ New Features
   Updated ena PMD with new features and improvements, including:
 
   * Added support for large LLQ (Low-latency queue) headers.
+  * Added Tx drops as new extended driver statistic.
 
 
 Removed Items
diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index 07feb62c3f..0d4523c1da 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -96,6 +96,7 @@ static const struct ena_stats ena_stats_global_strings[] = {
 	ENA_STAT_GLOBAL_ENTRY(wd_expired),
 	ENA_STAT_GLOBAL_ENTRY(dev_start),
 	ENA_STAT_GLOBAL_ENTRY(dev_stop),
+	ENA_STAT_GLOBAL_ENTRY(tx_drops),
 };
 
 static const struct ena_stats ena_stats_tx_strings[] = {
@@ -938,7 +939,7 @@ static void ena_stats_restart(struct rte_eth_dev *dev)
 	rte_atomic64_init(&adapter->drv_stats->ierrors);
 	rte_atomic64_init(&adapter->drv_stats->oerrors);
 	rte_atomic64_init(&adapter->drv_stats->rx_nombuf);
-	rte_atomic64_init(&adapter->drv_stats->rx_drops);
+	adapter->drv_stats->rx_drops = 0;
 }
 
 static int ena_stats_get(struct rte_eth_dev *dev,
@@ -972,7 +973,7 @@ static int ena_stats_get(struct rte_eth_dev *dev,
 					ena_stats.tx_bytes_low);
 
 	/* Driver related stats */
-	stats->imissed = rte_atomic64_read(&adapter->drv_stats->rx_drops);
+	stats->imissed = adapter->drv_stats->rx_drops;
 	stats->ierrors = rte_atomic64_read(&adapter->drv_stats->ierrors);
 	stats->oerrors = rte_atomic64_read(&adapter->drv_stats->oerrors);
 	stats->rx_nombuf = rte_atomic64_read(&adapter->drv_stats->rx_nombuf);
@@ -2785,12 +2786,16 @@ static void ena_keep_alive(void *adapter_data,
 	struct ena_adapter *adapter = adapter_data;
 	struct ena_admin_aenq_keep_alive_desc *desc;
 	uint64_t rx_drops;
+	uint64_t tx_drops;
 
 	adapter->timestamp_wd = rte_get_timer_cycles();
 
 	desc = (struct ena_admin_aenq_keep_alive_desc *)aenq_e;
 	rx_drops = ((uint64_t)desc->rx_drops_high << 32) | desc->rx_drops_low;
-	rte_atomic64_set(&adapter->drv_stats->rx_drops, rx_drops);
+	tx_drops = ((uint64_t)desc->tx_drops_high << 32) | desc->tx_drops_low;
+
+	adapter->drv_stats->rx_drops = rx_drops;
+	adapter->dev_stats.tx_drops = tx_drops;
 }
 
 /**
diff --git a/drivers/net/ena/ena_ethdev.h b/drivers/net/ena/ena_ethdev.h
index ed3674b202..5afce25f13 100644
--- a/drivers/net/ena/ena_ethdev.h
+++ b/drivers/net/ena/ena_ethdev.h
@@ -134,13 +134,19 @@ struct ena_driver_stats {
 	rte_atomic64_t ierrors;
 	rte_atomic64_t oerrors;
 	rte_atomic64_t rx_nombuf;
-	rte_atomic64_t rx_drops;
+	u64 rx_drops;
 };
 
 struct ena_stats_dev {
 	u64 wd_expired;
 	u64 dev_start;
 	u64 dev_stop;
+	/*
+	 * Tx drops cannot be reported as the driver statistic, because DPDK
+	 * rte_eth_stats structure isn't providing appropriate field for that.
+	 * As a workaround it is being published as an extended statistic.
+	 */
+	u64 tx_drops;
 };
 
 struct ena_offloads {
-- 
2.20.1