On 9/21/2020 10:59 AM, Junyu Jiang wrote:
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: sta...@dpdk.org
Signed-off-by: Junyu Jiang <junyux.ji...@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;
+}
+
I was more thinking reading stats and extending in same function,
instead of extracting the extending part into its own function, like:
static void
i40e_stat_update_48_in_64(struct i40e_hw *hw,
uint32_t hireg,
uint32_t loreg,
bool offset_loaded,
uint64_t *offset,
uint64_t *stat,
uint64_t *prev_bytes) {
i40e_stat_update_48(...)
/* logic to convert 'stat' to 64 bits */
}
Does it make sense?
