Re: net/virtio: duplicated xstats

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 11/24/2023 9:18 AM, Edwin Brossette wrote:
> Hello,
> 
> I noticed a small inconsistency in the virtio pmd's xstats.
> The stat "rx_q0_errors" appears twice.
> I also think the stats "rx_q0_packets", "rx_q0_bytes", "tx_q0_packets"
> and "tx_q0_bytes" are duplicates of "rx_q0_good_packets",
> "rx_q0_good_bytes", "tx_q0_good_packets" and "tx_q0_good_bytes"
> 

Ack, I didn't reproduce but from code I can see this inconsistency can
occur.


> I believe this issue probably appeared after this commit:
> 
> f30e69b41f94: ethdev: add device flag to bypass auto-filled queue xstats
> http://scm.6wind.com/vendor/dpdk.org/dpdk/commit/?id=f30e69b41f949cd4a9afb6ff39de196e661708e2 <http://scm.6wind.com/vendor/dpdk.org/dpdk/commit/?id=f30e69b41f949cd4a9afb6ff39de196e661708e2>
> 
> From what I understand, the rxq0_error stat was originally reported by
> the librte. However, changes were made so it is reported by the pmd instead.
> The flag RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS was temporarily set to keep
> the old behaviour so that every pmd could have time to adapt the change.
> But it seems the flag was forgotten in the virtio pmd and as a result,
> some stats are fetched at two different times when displaying xstats.
> 

Motivation is move queue stats from "basic stats" to "xstats".

'RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS' is a temporary flag, as you said,
and when driver sets it, ethdev layer copies queue stats from basic
stats to xstats.
In long term expectation is driver itself implement queue stats in
xstats and unset the flag, when all drivers implement this, flag will be
removed.


The issue with virtio is it already has queue stats in the xstats, with
the flag some queue stats duplicated.
It seems it is not forgotten to be removed, but it was mistake to add
flag at first place. So OK to remove the flag from virtio PMD.



> First in lib_rte_ethdev:
> https://git.dpdk.org/dpdk/tree/lib/ethdev/rte_ethdev.c#n3266
> <https://git.dpdk.org/dpdk/tree/lib/ethdev/rte_ethdev.c#n3266>
> (you can see the check on the RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS flag
> before the snprintf on |eth_dev_rxq_stats_strings[]| )
> 
> And a second time in the virtio pmd:
> https://git.dpdk.org/dpdk/tree/drivers/net/virtio/virtio_ethdev.c#n705
> <https://git.dpdk.org/dpdk/tree/drivers/net/virtio/virtio_ethdev.c#n705> pmd
> (see the snprintf on|rte_virtio_rxq_stat_strings|[] )
> 
> This problem can be reproduced on testpmd simply by displaying the
> xstats on a port with the net_virtio driver:
> 
> Reproduction:
> ===========
> 
>     1) start dpdk-testpmd:
> 
> modprobe -a uio_pci_generic
> dpdk-devbind -b uio_pci_generic 03:00.0
> dpdk-devbind -b uio_pci_generic 04:00.0
> 
> dpdk-devbind -s
> 
> Network devices using DPDK-compatible driver
> ============================================
> 0000:03:00.0 'Virtio 1.0 network device 1041' drv=uio_pci_generic
> unused=vfio-pci
> 0000:04:00.0 'Virtio 1.0 network device 1041' drv=uio_pci_generic
> unused=vfio-pci
> [...]
> 
> dpdk-testpmd -a 0000:03:00.0 -a 0000:04:00.0 -- -i --rxq=1 --txq=1
> --coremask=0x4 --total-num-mbufs=250000
> EAL: Detected CPU lcores: 3
> EAL: Detected NUMA nodes: 1
> EAL: Detected static linkage of DPDK
> EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
> EAL: Selected IOVA mode 'PA'
> EAL: VFIO support initialized
> EAL: Probe PCI driver: net_virtio (1af4:1041) device: 0000:03:00.0
> (socket -1)
> EAL: Probe PCI driver: net_virtio (1af4:1041) device: 0000:04:00.0
> (socket -1)
> Interactive-mode selected
> Warning: NUMA should be configured manually by using --port-numa-config
> and --ring-numa-config parameters along with --numa.
> testpmd: create a new mbuf pool <mb_pool_0>: n=250000, size=2176, socket=0
> testpmd: preferred mempool ops selected: ring_mp_mc
> Configuring Port 0 (socket 0)
> Port 0: 52:54:00:B0:8F:88
> Configuring Port 1 (socket 0)
> Port 1: 52:54:00:EF:09:1F
> Checking link statuses...
> Done
> 
>     2) port info:
> 
> show port info 0
> 
> ********************* Infos for port 0  *********************
> MAC address: 52:54:00:B0:8F:88
> Device name: 0000:03:00.0
> Driver name: net_virtio
> Firmware-version: not available
> Devargs:
> Connect to socket: 0
> memory allocation on the socket: 0
> Link status: up
> Link speed: Unknown
> Link duplex: full-duplex
> Autoneg status: On
> MTU: 1500
> Promiscuous mode: enabled
> Allmulticast mode: disabled
> Maximum number of MAC addresses: 64
> Maximum number of MAC addresses of hash filtering: 0
> VLAN offload:
>   strip off, filter off, extend off, qinq strip off
> No RSS offload flow type is supported.
> Minimum size of RX buffer: 64
> Maximum configurable length of RX packet: 9728
> Maximum configurable size of LRO aggregated packet: 0
> Current number of RX queues: 1
> Max possible RX queues: 1
> Max possible number of RXDs per queue: 32768
> Min possible number of RXDs per queue: 32
> RXDs number alignment: 1
> Current number of TX queues: 1
> Max possible TX queues: 1
> Max possible number of TXDs per queue: 32768
> Min possible number of TXDs per queue: 32
> TXDs number alignment: 1
> Max segment number per packet: 65535
> Max segment number per MTU/TSO: 65535
> Device capabilities: 0x0( )
> Device error handling mode: none
> Device private info:
> guest_features: 0x110af8020
> vtnet_hdr_size: 12
> use_vec: rx-0 tx-0
> use_inorder: rx-0 tx-0
> intr_lsc: 1
> max_mtu: 9698
> max_rx_pkt_len: 1530
> max_queue_pairs: 1
> req_guest_features: 0x8000005f10ef8028
> 
>     3) show port xstats:
> 
> show port xstats 0
> ###### NIC extended statistics for port 0
> rx_good_packets: 0
> tx_good_packets: 0
> rx_good_bytes: 0
> tx_good_bytes: 0
> rx_missed_errors: 0
> rx_errors: 0
> tx_errors: 0
> rx_mbuf_allocation_errors: 0
> rx_q0_packets: 0
> rx_q0_bytes: 0
> rx_q0_errors: 0      <==================
> tx_q0_packets: 0
> tx_q0_bytes: 0
> rx_q0_good_packets: 0
> rx_q0_good_bytes: 0
> rx_q0_errors: 0      <==================
> rx_q0_multicast_packets: 0
> rx_q0_broadcast_packets: 0
> rx_q0_undersize_packets: 0
> rx_q0_size_64_packets: 0
> rx_q0_size_65_127_packets: 0
> rx_q0_size_128_255_packets: 0
> rx_q0_size_256_511_packets: 0
> rx_q0_size_512_1023_packets: 0
> rx_q0_size_1024_1518_packets: 0
> rx_q0_size_1519_max_packets: 0
> tx_q0_good_packets: 0
> tx_q0_good_bytes: 0
> tx_q0_multicast_packets: 0
> tx_q0_broadcast_packets: 0
> tx_q0_undersize_packets: 0
> tx_q0_size_64_packets: 0
> tx_q0_size_65_127_packets: 0
> tx_q0_size_128_255_packets: 0
> tx_q0_size_256_511_packets: 0
> tx_q0_size_512_1023_packets: 0
> tx_q0_size_1024_1518_packets: 0
> tx_q0_size_1519_max_packets: 0
> 
> You can see the stat "rx_q0_errors" appeared twice.