[dpdk-users] RX of multi-segment jumbo frames

Filip Janiszewski contact at filipjaniszewski.com
Fri Feb 15 06:59:44 CET 2019

Unfortunately I didn't get much help from the maintainers at Mellanox,
but I discovered that with DPDK 18.05 there's the flag
ignore_offload_bitfield which once toggled to 1 along with the offloads
capture Jumbo on Mellanox:


In DPDK 19.02 this flag is missing and I can't capture Jumbos with my
current configuration.

Sadly, even if setting ignore_offload_bitfield to 1 fix my problem it
creates a bunch more, the packets coming in are not timestamped for
example (setting hw_timestamp to 1 does not fix the issue as the
timestamp are still EPOCH + some ms.).

Not sure if this can trigger any idea, for me it is not completely clear
what was the purpose of ignore_offload_bitfield (removed later) and how
to enable Jumbos properly.

What I've attempted so far (apart from the ignore_offload_bitfield):

1) Set mtu to 9600 (rte_eth_dev_set_mtu)
2) Configure port with offloads DEV_RX_OFFLOAD_SCATTER |
DEV_RX_OFFLOAD_JUMBO_FRAME, max_rx_pkt_len set to 9600
3) Configure RX queue with default_rxconf (from rte_eth_dev_info) adding
the offloads from the port configuration (DEV_RX_OFFLOAD_SCATTER |

The JF are reported as ierror in rte_eth_stats.


Il 09/02/19 16:36, Wiles, Keith ha scritto:
>> On Feb 9, 2019, at 9:27 AM, Filip Janiszewski <contact at filipjaniszewski.com> wrote:
>> Il 09/02/19 14:51, Wiles, Keith ha scritto:
>>>> On Feb 9, 2019, at 5:11 AM, Filip Janiszewski <contact at filipjaniszewski.com> wrote:
>>>> Hi,
>>>> I'm attempting to receive jumbo frames (~9000 bytes) on a Mellonox card
>>>> using DPDK, I've configured the DEV_RX_OFFLOAD_JUMBO_FRAME offload for
>>>> rte_eth_conf and rte_eth_rxconf (per RX Queue), but I can capture jumbo
>>>> frames only if the mbuf is large enough to contain the whole packet, is
>>>> there a way to enable DPDK to chain the incoming data in mbufs smaller
>>>> than the actual packet?
>>>> We don't have many of those big packets coming in, so would be optimal
>>>> to leave the mbuf size to RTE_MBUF_DEFAULT_BUF_SIZE and then configure
>>>> the RX device to chain those bufs for larger packets, but can't find a
>>>> way to do it, any suggestion?
>>> the best i understand is the nic or pmd needs to be configured to split up packets between mbufs in the rx ring. i look in the docs for the nic and see if it supports splitting up packets or ask the maintainer from the maintainers file.
>> I can capture jumbo packets with Wireshark on the same card (same port,
>> same setup), which let me think the problem is purely on my DPDK card
>> configuration.
>> According to ethtools, the jumbo packet (from now on JF, Jumbo Frame) is
>> detected at phy level, the couters rx_packets_phy, rx_bytes_phy,
>> rx_8192_to_10239_bytes_phy are properly increased.
>> There was an option to setup manually the support for JF but was remove
>> from DPDK after version 16.07: CONFIG_RTE_LIBRTE_MLX5_SGE_WR_N.
>> According to the release note:
>> .
>> Improved jumbo frames support, by dynamically setting RX scatter gather
>> elements according to the MTU and mbuf size, no need for compilation
>> parameter ``MLX5_PMD_SGE_WR_N``
>> .
>> Not quire sure where to look for..
> maintainer is your best bet now.
>>>> Thanks
>>>> -- 
>>>> BR, Filip
>>>> +48 666 369 823
>>> Regards,
>>> Keith
>> -- 
>> BR, Filip
>> +48 666 369 823
> Regards,
> Keith

BR, Filip
+48 666 369 823

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