[dpdk-users] mlx5: packets lost between good+discard and phy counters

[Tom Barbette]

CC-ing maintainers.

I did observe that too. rx_out_of_buffer is always 0 since a few months 
(I did not personnaly try to revert versions as Gerry did, I assume it 
was a DPDK update indeed as Gerry verified).


Tom

Le 11-04-21 à 03:31, Gerry Wan a écrit :
> After further investigation, I think this may be a bug introduced in DPDK
> v20.11, where these "lost" packets should be counted as "rx_out_of_buffer"
> and "rx_missed_errors". On v20.08 both of these counters increment, but 
on
> v20.11 and v21.02 these counters always remain 0.
>
> Any workarounds for this? This is an important statistic for my use case.
>
> On Fri, Apr 2, 2021 at 5:03 PM Gerry Wan <gerryw at stanford.edu> wrote:
>
>> I have a simple forwarding experiment using a mlx5 NIC directly connected
>> to a generator. I am noticing that at high enough throughput,
>> rx_good_packets + rx_phy_discard_packets may not equal rx_phy_packets.
>> Where are these packets being dropped?
>>
>> Below is an example xstats where I receive at almost the limit of what 
my
>> application can handle with no loss. It shows rx_phy_discard_packets is 0
>> but the number actually received by the CPU is less than rx_phy_packets.
>> rx_out_of_buffer and other errors are also 0.
>>
>> I have disabled Ethernet flow control via rte_eth_dev_flow_ctrl_set with
>> mode = RTE_FC_NONE, if that matters.
>>
>> {
>>      "rx_good_packets": 319992439,
>>      "tx_good_packets": 0,
>>      "rx_good_bytes": 19199546340,
>>      "tx_good_bytes": 0,
>>      "rx_missed_errors": 0,
>>      "rx_errors": 0,
>>      "tx_errors": 0,
>>      "rx_mbuf_allocation_errors": 0,
>>      "rx_q0_packets": 319992439,
>>      "rx_q0_bytes": 19199546340,
>>      "rx_q0_errors": 0,
>>      "rx_wqe_errors": 0,
>>      "rx_unicast_packets": 319999892,
>>      "rx_unicast_bytes": 19199993520,
>>      "tx_unicast_packets": 0,
>>      "tx_unicast_bytes": 0,
>>      "rx_multicast_packets": 0,
>>      "rx_multicast_bytes": 0,
>>      "tx_multicast_packets": 0,
>>      "tx_multicast_bytes": 0,
>>      "rx_broadcast_packets": 0,
>>      "rx_broadcast_bytes": 0,
>>      "tx_broadcast_packets": 0,
>>      "tx_broadcast_bytes": 0,
>>      "tx_phy_packets": 0,
>>      "rx_phy_packets": 319999892,
>>      "rx_phy_crc_errors": 0,
>>      "tx_phy_bytes": 0,
>>      "rx_phy_bytes": 20479993088,
>>      "rx_phy_in_range_len_errors": 0,
>>      "rx_phy_symbol_errors": 0,
>>      "rx_phy_discard_packets": 0,
>>      "tx_phy_discard_packets": 0,
>>      "tx_phy_errors": 0,
>>      "rx_out_of_buffer": 0,
>>      "tx_pp_missed_interrupt_errors": 0,
>>      "tx_pp_rearm_queue_errors": 0,
>>      "tx_pp_clock_queue_errors": 0,
>>      "tx_pp_timestamp_past_errors": 0,
>>      "tx_pp_timestamp_future_errors": 0,
>>      "tx_pp_jitter": 0,
>>      "tx_pp_wander": 0,
>>      "tx_pp_sync_lost": 0,
>> }
>>
>>