[dpdk-dev] [PATCH v3] net/i40e: fix incorrect byte counters

[Junyu Jiang <junyux.jiang@intel.com>]

This patch fixed the issue that rx/tx bytes statistics counters
overflowed on 48 bit limitation by enlarging the limitation.

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Cc: stable@dpdk.org

Signed-off-by: Junyu Jiang <junyux.jiang@intel.com>
---
 doc/guides/nics/i40e.rst       |  7 +++++++
 drivers/net/i40e/i40e_ethdev.c | 32 ++++++++++++++++++++++++++++++++
 drivers/net/i40e/i40e_ethdev.h |  9 +++++++++
 3 files changed, 48 insertions(+)

diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
index b7430f6c4..4baa58be6 100644
--- a/doc/guides/nics/i40e.rst
+++ b/doc/guides/nics/i40e.rst
@@ -830,3 +830,10 @@ Tx bytes affected by the link status change
 
 For firmware versions prior to 6.01 for X710 series and 3.33 for X722 series, the tx_bytes statistics data is affected by
 the link down event. Each time the link status changes to down, the tx_bytes decreases 110 bytes.
+
+RX/TX statistics may be incorrect when register overflowed
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The rx_bytes/tx_bytes statistics register is 48 bit length. Although this limitation is enlarged to 64 bit length
+on the software side, but there is no way to detect if the overflow occurred more than once. So rx_bytes/tx_bytes
+statistics data is correct when statistics are updated at least once between two overflows.
diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
index 563f21d9d..212338ef0 100644
--- a/drivers/net/i40e/i40e_ethdev.c
+++ b/drivers/net/i40e/i40e_ethdev.c
@@ -3052,6 +3052,19 @@ i40e_dev_link_update(struct rte_eth_dev *dev,
 	return ret;
 }
 
+static void
+i40e_stat_update_48_in_64(uint64_t *new_bytes,
+			  uint64_t *prev_bytes,
+			  bool offset_loaded)
+{
+	if (offset_loaded) {
+		if (I40E_RXTX_BYTES_L_48_BIT(*prev_bytes) > *new_bytes)
+			*new_bytes += (uint64_t)1 << I40E_48_BIT_WIDTH;
+		*new_bytes += I40E_RXTX_BYTES_H_16_BIT(*prev_bytes);
+	}
+	*prev_bytes = *new_bytes;
+}
+
 /* Get all the statistics of a VSI */
 void
 i40e_update_vsi_stats(struct i40e_vsi *vsi)
@@ -3073,6 +3086,9 @@ i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	i40e_stat_update_48(hw, I40E_GLV_BPRCH(idx), I40E_GLV_BPRCL(idx),
 			    vsi->offset_loaded, &oes->rx_broadcast,
 			    &nes->rx_broadcast);
+	/* enlarge the limitation when rx_bytes overflowed */
+	i40e_stat_update_48_in_64(&nes->rx_bytes, &vsi->prev_rx_bytes,
+				  vsi->offset_loaded);
 	/* exclude CRC bytes */
 	nes->rx_bytes -= (nes->rx_unicast + nes->rx_multicast +
 		nes->rx_broadcast) * RTE_ETHER_CRC_LEN;
@@ -3099,6 +3115,9 @@ i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	/* GLV_TDPC not supported */
 	i40e_stat_update_32(hw, I40E_GLV_TEPC(idx), vsi->offset_loaded,
 			    &oes->tx_errors, &nes->tx_errors);
+	/* enlarge the limitation when tx_bytes overflowed */
+	i40e_stat_update_48_in_64(&nes->tx_bytes, &vsi->prev_tx_bytes,
+				  vsi->offset_loaded);
 	vsi->offset_loaded = true;
 
 	PMD_DRV_LOG(DEBUG, "***************** VSI[%u] stats start *******************",
@@ -3171,6 +3190,13 @@ i40e_read_stats_registers(struct i40e_pf *pf, struct i40e_hw *hw)
 			    pf->offset_loaded,
 			    &pf->internal_stats_offset.tx_broadcast,
 			    &pf->internal_stats.tx_broadcast);
+	/* enlarge the limitation when internal rx/tx bytes overflowed */
+	i40e_stat_update_48_in_64(&pf->internal_stats.rx_bytes,
+				  &pf->internal_prev_rx_bytes,
+				  pf->offset_loaded);
+	i40e_stat_update_48_in_64(&pf->internal_stats.tx_bytes,
+				  &pf->internal_prev_tx_bytes,
+				  pf->offset_loaded);
 
 	/* exclude CRC size */
 	pf->internal_stats.rx_bytes -= (pf->internal_stats.rx_unicast +
@@ -3194,6 +3220,9 @@ i40e_read_stats_registers(struct i40e_pf *pf, struct i40e_hw *hw)
 			    I40E_GLPRT_BPRCL(hw->port),
 			    pf->offset_loaded, &os->eth.rx_broadcast,
 			    &ns->eth.rx_broadcast);
+	/* enlarge the limitation when rx_bytes overflowed */
+	i40e_stat_update_48_in_64(&ns->eth.rx_bytes, &pf->prev_rx_bytes,
+				  pf->offset_loaded);
 	/* Workaround: CRC size should not be included in byte statistics,
 	 * so subtract RTE_ETHER_CRC_LEN from the byte counter for each rx
 	 * packet.
@@ -3252,6 +3281,9 @@ i40e_read_stats_registers(struct i40e_pf *pf, struct i40e_hw *hw)
 			    I40E_GLPRT_BPTCL(hw->port),
 			    pf->offset_loaded, &os->eth.tx_broadcast,
 			    &ns->eth.tx_broadcast);
+	/* enlarge the limitation when tx_bytes overflowed */
+	i40e_stat_update_48_in_64(&ns->eth.tx_bytes, &pf->prev_tx_bytes,
+				  pf->offset_loaded);
 	ns->eth.tx_bytes -= (ns->eth.tx_unicast + ns->eth.tx_multicast +
 		ns->eth.tx_broadcast) * RTE_ETHER_CRC_LEN;
 
diff --git a/drivers/net/i40e/i40e_ethdev.h b/drivers/net/i40e/i40e_ethdev.h
index 19f821829..1466998aa 100644
--- a/drivers/net/i40e/i40e_ethdev.h
+++ b/drivers/net/i40e/i40e_ethdev.h
@@ -282,6 +282,9 @@ struct rte_flow {
 #define I40E_ETH_OVERHEAD \
 	(RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN + I40E_VLAN_TAG_SIZE * 2)
 
+#define I40E_RXTX_BYTES_H_16_BIT(bytes) ((bytes) & ~I40E_48_BIT_MASK)
+#define I40E_RXTX_BYTES_L_48_BIT(bytes) ((bytes) & I40E_48_BIT_MASK)
+
 struct i40e_adapter;
 struct rte_pci_driver;
 
@@ -399,6 +402,8 @@ struct i40e_vsi {
 	uint8_t vlan_anti_spoof_on; /* The VLAN anti-spoofing enabled */
 	uint8_t vlan_filter_on; /* The VLAN filter enabled */
 	struct i40e_bw_info bw_info; /* VSI bandwidth information */
+	uint64_t prev_rx_bytes;
+	uint64_t prev_tx_bytes;
 };
 
 struct pool_entry {
@@ -1156,6 +1161,10 @@ struct i40e_pf {
 	uint16_t switch_domain_id;
 
 	struct i40e_vf_msg_cfg vf_msg_cfg;
+	uint64_t prev_rx_bytes;
+	uint64_t prev_tx_bytes;
+	uint64_t internal_prev_rx_bytes;
+	uint64_t internal_prev_tx_bytes;
 };
 
 enum pending_msg {
-- 
2.17.1