[dpdk-users] Unable to merge packets using GRO feature

Hu, Jiayu jiayu.hu at intel.com
Thu Sep 7 03:14:34 CEST 2017
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Hi Wisam,

When we perform a similar test on i40e, we find an important thing:
there is a max number limit for mbuf->nb_segs. When the number of MBUF segments
of the packet is larger than this limit, the packet will be dropped.

The GROed packet has multiple MBUF segments. For vhost-dpdk, it doesn't have limit for
the number of segments. But it's not the same for all NIC drivers. So I suggest you to check
if the MLX driver has this limit too.

Thanks,
Jiayu

> -----Original Message-----
> From: Wisam Monther [mailto:wisamm at mellanox.com]
> Sent: Wednesday, September 6, 2017 7:18 PM
> To: Hu, Jiayu <jiayu.hu at intel.com>
> Cc: users at dpdk.org; Raslan Darawsheh <rasland at mellanox.com>; Shahaf
> Shuler <shahafs at mellanox.com>
> Subject: RE: Unable to merge packets using GRO feature
> 
> Hi Jiayu,
> 
> Any comment regard what I described?
> 
> BRs,
> Wisam Jaddo
> 
> -----Original Message-----
> From: Wisam Monther
> Sent: Tuesday, August 29, 2017 10:49 AM
> To: 'Hu, Jiayu'
> Cc: users at dpdk.org; Raslan Darawsheh; Shahaf Shuler
> Subject: RE: Unable to merge packets using GRO feature
> 
> Hi Jiayu,
> 
> Let me re-describe my topology in a better way, see attached image.
> And it is connected physically as described, and I'm using it with MTU
> size=1500 in order to make sure Every port can handle it.
> 
> And this is the exact connection between the interfaces, so I'm sure the
> packets received in NIC B machine B is coming from the testpmd with GRO
> enabled.
> 
> But even so, I intentionally made the packet size 1500, to be divided into 3 *
> ( 500) fragments using the TSO, and then merged into 1500 packet again in
> the GRO.
> So the every machine can manage this mtu size.
> 
> The thing that I need to test GRO with each setups types, "VMs with
> Baremetal with pass through with VFs etc...".
> So I need to see the feature works on least work, it would be nice to send
> IPV4_TCP fragmented packet using "scapy, Iperf"
> And check the fwd packet from GRO directly.
> 
> BRs,
> Wisam Jaddo
> 
> -----Original Message-----
> From: Hu, Jiayu [mailto:jiayu.hu at intel.com]
> Sent: Tuesday, August 29, 2017 4:51 AM
> To: Wisam Monther
> Cc: users at dpdk.org; Raslan Darawsheh; Shahaf Shuler
> Subject: RE: Unable to merge packets using GRO feature
> 
> Hi Wisam,
> 
> In the picture of your experiment topology, I guess NIC B in the machine B is
> connected with another interface physically. If so, the packets that tcpdump
> captures are from the physical link. However, packets after GROed are multi-
> segment large packets, which are larger than MTU. I am not sure if you have
> make other configurations to enable these large packets to pass the physical
> link, and there is jumbo frame size limit for different NICs. So would you
> please to check this? BTW, you can use the VM to test this GRO feature,
> since large packets can always pass to the VM.
> 
> Thanks,
> Jiayu
> 
> > -----Original Message-----
> > From: Wisam Monther [mailto:wisamm at mellanox.com]
> > Sent: Monday, August 28, 2017 3:37 PM
> > To: Hu, Jiayu <jiayu.hu at intel.com>
> > Cc: users at dpdk.org; Raslan Darawsheh <rasland at mellanox.com>; Shahaf
> > Shuler <shahafs at mellanox.com>
> > Subject: RE: Unable to merge packets using GRO feature
> >
> > Hi Jiayu,
> >
> > I'm sorry for bothering you, but could you conform that the feature is
> > working probably Because, what I ever  did, I couldn't get the merged
> > packets.
> >
> > BRs,
> > Wisam Jaddo
> >
> > -----Original Message-----
> > From: Wisam Monther
> > Sent: Thursday, August 24, 2017 9:15 AM
> > To: 'Hu, Jiayu'
> > Cc: users at dpdk.org; Raslan Darawsheh; Shahaf Shuler
> > Subject: RE: Unable to merge packets using GRO feature
> >
> > Hi,
> >
> > I'm using Mellanox NICs, and it is supporting parse packet types.
> >
> > Best regards,
> > Wisam Jaddo
> >
> > -----Original Message-----
> > From: Hu, Jiayu [mailto:jiayu.hu at intel.com]
> > Sent: Thursday, August 24, 2017 8:47 AM
> > To: Wisam Monther
> > Cc: users at dpdk.org; Raslan Darawsheh; Shahaf Shuler
> > Subject: RE: Unable to merge packets using GRO feature
> >
> > Hi,
> >
> > Can you tell me what's the NIC type of the GRO-enabled port?
> >
> > Since GRO library uses mbuf->packet_type to parse packet headers,
> > applications need to fill this value before calling GRO reassembly APIs.
> > Otherwise, the GRO can't work correctly.
> >
> > In csum forwarding engine of testpmd, packet_type is filled by NIC drivers.
> > The csum forwarding engine won't set this value. So if your NIC
> > doesn’t support to parse packet types, the value of packet_type is 0
> > and GRO can't work correctly.
> >
> > BRs,
> > Jiayu
> >
> > > -----Original Message-----
> > > From: Wisam Monther [mailto:wisamm at mellanox.com]
> > > Sent: Tuesday, August 22, 2017 9:25 PM
> > > To: Hu, Jiayu <jiayu.hu at intel.com>
> > > Cc: users at dpdk.org; Raslan Darawsheh <rasland at mellanox.com>;
> Shahaf
> > > Shuler <shahafs at mellanox.com>
> > > Subject: RE: Unable to merge packets using GRO feature
> > >
> > > Yes it is,
> > > The fragmented packets comes from port1 / NIC b from machine A to
> > > port
> > > 1 in NIC A for machine b So it's received on the port '1', which is
> > > configured gro active on this port.
> > >
> > > Best regards,
> > > Wisam Jaddo
> > >
> > > -----Original Message-----
> > > From: Hu, Jiayu [mailto:jiayu.hu at intel.com]
> > > Sent: Tuesday, August 22, 2017 4:21 PM
> > > To: Wisam Monther
> > > Cc: users at dpdk.org; Raslan Darawsheh; Shahaf Shuler
> > > Subject: RE: Unable to merge packets using GRO feature
> > >
> > > Hi,
> > >
> > > > -----Original Message-----
> > > > From: Wisam Monther [mailto:wisamm at mellanox.com]
> > > > Sent: Tuesday, August 22, 2017 7:07 PM
> > > > To: Hu, Jiayu <jiayu.hu at intel.com>
> > > > Cc: users at dpdk.org; Raslan Darawsheh <rasland at mellanox.com>;
> > Shahaf
> > > > Shuler <shahafs at mellanox.com>
> > > > Subject: RE: Unable to merge packets using GRO feature
> > > >
> > > > Hey Jiayu,
> > > >
> > > > Thank you for your reply.
> > > > I tried what you said with the csum at fwd mode.
> > > > Even so the GRO didn't works fine.
> > > >
> > > > I even tested with a new methodology.
> > > > Two machines with two different nic for each.
> > > > The methodology that I used to test it is described in the attached file.
> > > >
> > > > What I did from gro side:
> > > > """
> > > > testpmd>gro on 1
> > >
> > > Does the port number of NIC A in machine B is '1'? When you enable
> > > GRO for port '1', Testpmd only tries to merge packets received from port
> '1'.
> > >
> > > BRs,
> > > Jiayu
> > >
> > > > Testpmd>set fwd csum
> > > > Testpmd>start
> > > > """
> > > > And the packet with correct dst mac.
> > > >
> > > > Best regards,
> > > > Wisam Jaddo
> > > > -----Original Message-----
> > > > From: Jiayu Hu [mailto:jiayu.hu at intel.com]
> > > > Sent: Monday, August 21, 2017 12:14 PM
> > > > To: Wisam Monther
> > > > Cc: Thomas Monjalon; users at dpdk.org; Raslan Darawsheh; Shahaf
> > > > Shuler
> > > > Subject: Re: Unable to merge packets using GRO feature
> > > >
> > > > Hi,
> > > >
> > > > On Mon, Aug 21, 2017 at 07:25:23AM +0000, Wisam Monther wrote:
> > > > > Hello Guys,
> > > > >
> > > > >
> > > > >
> > > > > I hope this finds you well, I’m trying to test the GRO feature.
> > > > > But I’m stuck with this scenario.
> > > > >
> > > > > As you know, GRO is only support TCP_IPV4 packet until now.
> > > > >
> > > > > So I’m trying to test the basic functionality of the feature, as
> following:
> > > > >
> > > > > Start testpmd:
> > > > >
> > > > > “””
> > > > >
> > > > > ./x86_64-native-linuxapp-gcc/build/app/test-pmd/testpmd -n 4  -w
> > > > > 00:0a.0  -w
> > > > > 00:09.0 --  --burst=64 --mbcache=512 --portmask 0xf -i
> > > > > --txd=512
> > > > > --rxd=512
> > > > > --nb-cores=9  --rxq=2 --txq=2 --txqflags=0
> > > > >
> > > > > “””
> > > > >
> > > > >
> > > > >
> > > > > Then enable GRO at the two ports:
> > > > >
> > > > > “””
> > > > >
> > > > > Testpmd>gro on 0
> > > > >
> > > > > Testpmd>gro on 1
> > > >
> > > > When use GRO in testpmd, there are following things to notice:
> > > >
> > > > 1. In testpmd, GRO is supported by csum forwarding engine.
> > > > Therefore, please use 'set fwd csum' to switch forwarding engine.
> > > >
> > > > 2. By default, csum forwarding engine compulsorily changes
> > > > ethernet addresses. So please make sure that MAC addresses are
> correct.
> > > >
> > > > 3. When enable GRO for port0, csum forwarding engine will merge
> > > > packets received from port0. If there are no packets from port1 to
> > > > port0, you don't need to enable GRO for port1.
> > > >
> > > > 4. GRO library doesn't re-calculate checksums for merged packets.
> > > > If you want merged packets have correct checksum, please select HW
> > > > IP and HW TCP checksum calculation for the port which the merged
> > > > packets are transmitted to in csum forwarding engine.
> > > > This is because the merged packets are multi-segment mbufs, but
> > > > csum forwarding engine doesn't support to calculate checksums for
> > > > multi-segment mbufs in SW. So we need to select HW checksum
> > offloading.
> > > >
> > > > e.g. If data flow is "packets -> port0 -> port1", commands used in
> > testpmd:
> > > > 	gro on port0
> > > > 	set fwd csum
> > > > 	csum set ip hw port1
> > > > 	csum set tcp hw port1
> > > >
> > > >
> > > > Besides, you need to make sure that your PMD driver doesn't use
> > > > vector TX function, since vector function doesn't support checksum
> > offloading.
> > > >
> > > > >
> > > > > “””
> > > > >
> > > > >
> > > > >
> > > > > And trying to send TCP_IPV4 fragmented packet “packet with
> > > > > length
> > > > > 1500 fragmented to three packets of 500”
> > > > >
> > > > > “””
> > > > >
> > > > > p=Ether(src=get_if_hwaddr('ens10'), dst=
> > > > > '24:8A:07:88:26:6B')/IP()/TCP()
> > > > >
> > > > > p.add_payload('F'*(1500 - len(p)))
> > > > >
> > > > > frags=fragment(p,fragsize=500)
> > > > >
> > > > > for fragment in frags:
> > > > >
> > > > >      sendp(fragment, iface='ens10')
> > > > >
> > > > > “””
> > > > >
> > > > >
> > > > >
> > > > > But the testpmd forward the packets as it is, “ doesn’t do any merge”
> > > > >
> > > > >
> > > > >
> > > > > Tcpdump at the TG side,
> > > > >
> > > > > The sending fragmets using ens10:
> > > > >
> > > > > #tcpdump –I ens10 –vvven
> > > > >
> > > > > 15:45:29.083514 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 538: (tos 0x0, ttl 64, id 1, offset 0,
> > > > > flags [+], proto Options (0), length 524)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1:  ip-proto-0 504
> > > > >
> > > > > 15:45:29.115266 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 538: (tos 0x0, ttl 64, id 1, offset 504,
> > > > > flags [+], proto Options (0), length 524)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1: ip-proto-0
> > > > >
> > > > > 15:45:29.147258 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 492: (tos 0x0, ttl 64, id 1, offset 1008,
> > > > > flags [none], proto Options (0), length 478)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1: ip-proto-0
> > > > >
> > > > >
> > > > >
> > > > > #tcpdump -i ens9 –vvven  /// here will be received the forwarded
> > > > > packets from
> > > > > testpmd:
> > > > >
> > > > > 15:45:29.083996 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 538: (tos 0x0, ttl 64, id 1, offset 0,
> > > > > flags [+], proto Options (0), length 524)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1:  ip-proto-0 504
> > > > >
> > > > > 15:45:29.115425 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 538: (tos 0x0, ttl 64, id 1, offset 504,
> > > > > flags [+], proto Options (0), length 524)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1: ip-proto-0
> > > > >
> > > > > 15:45:29.147492 24:8a:07:88:26:5b > 24:8a:07:88:26:6b, ethertype
> > > > > IPv4 (0x0800), length 492: (tos 0x0, ttl 64, id 1, offset 1008,
> > > > > flags [none], proto Options (0), length 478)
> > > > >
> > > > >     127.0.0.1 > 127.0.0.1: ip-proto-0
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Am I doing something wrong?! Or it is a bug.
> > > > >
> > > > > è As you see the tcpdump shows the offset of each fragment, and
> > > > > testpmd prints L4_FRAG, so the both are recognizing that this is
> > > > > a
> > > > fragmented packet.
> > > >
> > > > GRO library merges TSOed/GSOed packets, whose IP IDs and TCP
> > > sequences
> > > > are both consecutive. If input packets have same IP IDs, no
> > > > packets will be merged.
> > > >
> > > > BTW, you can use iperf to test GRO feature.
> > > >
> > > > Best Regards,
> > > > Jiayu
> > > >
> > > > >
> > > > >
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Wisam Jaddo
> > > > >
> > > > >
> > > > >
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