[ovs-discuss] OVS-DPDK - Very poor performance when connected to namespace/container

Avi Cohen (A) avi.cohen at huawei.com
Thu Jun 15 08:49:36 UTC 2017

> -----Original Message-----
> From: Mooney, Sean K [mailto:sean.k.mooney at intel.com]
> Sent: Thursday, 15 June, 2017 11:24 AM
> To: Avi Cohen (A); dpdk-ovs at lists.01.org; users at dpdk.org; ovs-
> discuss at openvswitch.org
> Cc: Mooney, Sean K
> Subject: RE: OVS-DPDK - Very poor performance when connected to
> namespace/container
> > -----Original Message-----
> > From: Dpdk-ovs [mailto:dpdk-ovs-bounces at lists.01.org] On Behalf Of Avi
> > Cohen (A)
> > Sent: Thursday, June 15, 2017 8:14 AM
> > To: dpdk-ovs at lists.01.org; users at dpdk.org; ovs-discuss at openvswitch.org
> > Subject: [Dpdk-ovs] OVS-DPDK - Very poor performance when connected to
> > namespace/container
> >
> > Hello   All,
> > I have OVS-DPDK connected to a namespace via veth pair device.
> >
> > I've got a very poor performance - compared to normal OVS (i.e. no
> > DPDK).
> > For example - TCP jumbo pkts throughput: normal OVS  ~ 10Gbps , OVS-
> > DPDK 1.7 Gbps.
> >
> > This can be explained as follows:
> > veth is implemented in kernel - in OVS-DPDK data is transferred from
> > veth to user space while in normal OVS we save this transfer
> [Mooney, Sean K] that is part of the reason, the other reson this is slow and The
> main limiter to scalling adding veth pairs or ovs internal port to ovs with dpdk is
> That these linux kernel ports are not processed by the dpdk pmds. They are
> server by the Ovs-vswitchd main thread via a fall back to the non dpdk
> acclarated netdev implementation.
> >
> > Is there any other device to connect to namespace ? something like
> > vhost-user ? I understand that vhost-user cannot be used for namespace
> [Mooney, Sean K] I have been doing some experiments in this regard.
> You should be able to use the tap, pcap or afpacket pmd to add a vedv that will
> improve Performance. I have seen some strange issue with the tap pmd that
> cause packet to be drop By the kernel on tx on some ports but not others so
> there may be issues with that dirver.
> Previous experiment with libpcap seemed to work well with ovs 2.5 but I have
> not tried it With ovs 2.7/master since the introduction of generic vdev support
> at runtime. Previously vdevs And to be allocated using the dpdk args.
> I would try following the af_packet example here
> https://github.com/openvswitch/ovs/blob/b132189d8456f38f3ee139f126d6809
> 01a9ee9a8/Documentation/howto/dpdk.rst#vdev-support
[Avi Cohen (A)] 
Thank you Mooney, Sean K
I already tried to connect the namespace with a tap device (see 1 & 2 below)  - and got the worst performance 
 for some reason the packet  is cut to default MTU inside the  OVS-DPDK which transmit the packet to its peer. - although all interfaces MTU were set to 9000.

 1. ovs-vsctl add-port $BRIDGE tap1 -- set Interface tap1 type=internal
 2. ip link set tap1 netns ns1 // attach it to namespace

I'm looking at your link to create a virtual PMD with vdev support - I see there a creation of a virtual PMD device , but I'm not sure how this is connected to the namespace ?  what device should I assign to the namespace ? 

Best Regards

> if you happen to be investigating this for use with openstack routers we Are
> currently working on a way to remove the use of namespace entirely for dvr
> when using The default neutron agent and sdn controllers such as ovn already
> provide that functionality.
> >
> > Best Regards
> > avi
> > _______________________________________________
> > Dpdk-ovs mailing list
> > Dpdk-ovs at lists.01.org
> > https://lists.01.org/mailman/listinfo/dpdk-ovs

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