>From: Nitin Katiyar [mailto:[email protected]]
>Sent: Monday, September 18, 2017 3:20 PM
>To: Kavanagh, Mark B <[email protected]>; [email protected]
>Subject: RE: [ovs-dev] MTU in i40e dpdk driver
>
>Hi,
>Yes, the tag is configured for VHU port so traffic from VM would be tagged
>with vlan. Why is it different from 10G (ixgbe) driver? It should allow the
>packet matching with the configured MTU. Is it expected behavior with i40e
>driver?
In this instance, the behavior is determined by OvS, and not the DPDK driver;
see the code snippets below from netdev-dpdk.c:
<snip>
#define MTU_TO_FRAME_LEN(mtu) ((mtu) + ETHER_HDR_LEN + ETHER_CRC_LEN)
# As you can see, the VLAN header is not accounted for as part of a packet's
overhead
</snip>
...
<snip>
static int
netdev_dpdk_mempool_configure(struct netdev_dpdk *dev)
OVS_REQUIRES(dpdk_mutex)
OVS_REQUIRES(dev->mutex)
{
...
dpdk_mp_put(dev->dpdk_mp);
dev->dpdk_mp = mp;
dev->mtu = dev->requested_mtu;
dev->socket_id = dev->requested_socket_id;
dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu);
# This line uses the MTU_TO_FRAME_LEN macro to set the upper
size limit on packets that the NIC will accept.
# The NIC is subsequently configured with this value.
...
}
</snip>
...
<snip>
static int
dpdk_eth_dev_queue_setup(struct netdev_dpdk *dev, int n_rxq, int n_txq)
{
...
if (dev->mtu > ETHER_MTU) {
conf.rxmode.jumbo_frame = 1;
conf.rxmode.max_rx_pkt_len = dev->max_packet_len;
# max Rx packet length is set in NIC's config. object.
...
diag = rte_eth_dev_configure(dev->port_id, n_rxq, n_txq,
&conf); # NIC's max Rx packet length is actually set.
...
}
</snip>
Hope this helps,
Mark
>
>Thanks,
>Nitin
>
>-----Original Message-----
>From: Kavanagh, Mark B [mailto:[email protected]]
>Sent: Monday, September 18, 2017 7:44 PM
>To: Nitin Katiyar <[email protected]>; [email protected]
>Subject: RE: [ovs-dev] MTU in i40e dpdk driver
>
>>From: Nitin Katiyar [mailto:[email protected]]
>>Sent: Monday, September 18, 2017 3:02 PM
>>To: Kavanagh, Mark B <[email protected]>;
>>[email protected]
>>Subject: RE: [ovs-dev] MTU in i40e dpdk driver
>>
>>Hi,
>>It is set to 2140.
>
>That should accommodate a max packet length of 2158 (i.e. MTU + ETHER_HDR
>(14B) + ETHER_CRC (4B)).
>
>Is the VM inside a VLAN by any chance? The presence of a VLAN tag would
>account for the additional 4B.
>
>-Mark
>
>>
>>compute-0-4:~# ovs-vsctl get Interface dpdk1 mtu
>>2140
>>
>>Regards,
>>Nitin
>>
>>-----Original Message-----
>>From: Kavanagh, Mark B [mailto:[email protected]]
>>Sent: Monday, September 18, 2017 7:26 PM
>>To: Nitin Katiyar <[email protected]>; [email protected]
>>Subject: Re: [ovs-dev] MTU in i40e dpdk driver
>>
>>>From: [email protected]
>>>[mailto:[email protected]]
>>>On Behalf Of Nitin Katiyar
>>>Sent: Monday, September 18, 2017 2:05 PM
>>>To: [email protected]
>>>Subject: [ovs-dev] MTU in i40e dpdk driver
>>>
>>>Hi,
>>>We are using OVS-DPDK (2.6 version) with Fortville NIC (configured in
>>>25G
>>>mode) being used as dpdk port. The setup involves 2 VMs running on 2
>>>different computes (destination VM in compute with 10G NIC while
>>>originating VM is in compute with Fortville NIC). All the interfaces
>>>in the path are configured with MTU of 2140.
>>>
>>>While pinging with size of 2112 (IP packet of 2140 bytes) we found
>>>that ping response does not reach originating VM (i.e on compute with
>>>Fortville
>>NIC) .
>>>DPDK interface does not show any drop but we don't see any ping
>>>response received at DPDK port (verified using port-mirroring). We
>>>also don't see any rule in ovs dpctl for ping response. If we increase
>>>the MTU of DPDK interface by 4 bytes or reduce the ping size by 4
>>>bytes then it
>>works.
>>>
>>>The same configuration works between 10G NICs on both sides.
>>>
>>>Is it a known issue with i40 dpdk driver?
>>
>>Hi Nitin,
>>
>>What is the MTU of the DPDK ports in this setup?
>>
>> ovs-vscl get Interface <iface_name> mtu
>>
>>Thanks,
>>Mark
>>
>>>
>>>Regards,
>>>Nitin
>>>_______________________________________________
>>>dev mailing list
>>>[email protected]
>>>https://mail.openvswitch.org/mailman/listinfo/ovs-dev
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