[ovs-discuss] OVS DPDK performance for TCP traffic versus UDP

Michael Richardson mcr at sandelman.ca
Thu Oct 4 15:01:51 UTC 2018


Onkar Pednekar <onkar3006 at gmail.com> wrote:
    > I have been experimenting with OVS DPDK on 1G interfaces. The system
    > has 8 cores (hyperthreading enabled) mix of dpdk and non-dpdk capable
    > ports, but the data traffic runs only on dpdk ports.

    > DPDK ports are backed by vhost user netdev and I have configured the
    > system so that hugepages are enabled, CPU cores isolated with PMD
    > threads allocated to them and also pinning the VCPUs.

    > When I run UDP traffic, I see ~ 1G throughput on dpdk interfaces with <
    > 1% packet loss. However, with tcp traffic, I see around 300Mbps

What size packet?
What's your real pps?
What do you do for test traffic?
What is your latency?  Are there queues full?
Are you layer-2 switching or layer-3 routing, or something exotic?

    > thoughput. I see that setting generic receive offload to off helps, but
    > still the TCP thpt is very less compared to the nic capabilities.  I
    > know that there will be some performance degradation for TCP as against
    > UDP but this is way below expected.

Receive offload should only help if you are terminating the TCP flows.
I could well see that it would affect a switching situation significantly.
What are you using for TCP flow generation?  Are you running real TCP
stacks with window calculations and back-off, etc?  Is your offered load
actually going up?

    > I don't see any packets dropped for tcp on the internal VM (virtual)
    > interfaces.

?virtual?
I don't understand: do you have senders/receivers on the machine under test?

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     mcr at sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [


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