[dpdk-dev] rte_eth_rx bug? duplicate message bufs

[Lavanya Jose]

Hi,

I was wondering if anyone on this list has come across this problem of
rte_eth_rx_burst returning the same mbuf contents multiple times especially
during congestion. I notice this problem after some number of calls to
rte_eth_rx_burst when I set the nb_pkts argument to anything more than 5. I
did confirm that the contents (random payloads) in the duplicate packets
are identical.

I looked at the corresponding ixgbe driver code that gets packets from the
rx ring.
<https://github.com/emmericp/dpdk/blob/e5b112e4c7a4d63f3131294e9611e4a892b75008/drivers/net/ixgbe/ixgbe_rxtx.c#L1595>
It looks like the driver doesn't drop packets if an mbuf allocation fails.
I'm not sure if this is the root cause of the bug I'm seeing?

I'm also curious about whether I need to set rx_descs and tx_descs to 40
when I'm setting up the Intel 82599 device? The datasheet says there's 40
descriptors per TX queue though default values I've seen in code are much
larger..

Thanks,
Lavanya