[ovs-discuss] ovs-dpdk performance not stable

[Stokes, Ian]

Hi Michael,

Are you using dpdk vhostuser ports in this deployment?

I would expect to see them listed in the output of ovs-appctl dpif-netdev/pmd-rxq-show you posted below.

Can you describe the expected traffic flow ( Is it North/South using DPDK phy devices as well as vhost devices or east/west between vm interfaces only).

OVS 2.6 has the ability to isolate and pin rxq queues for dpdk devices to specific PMDs also. This can help provide more stable throughput and defined behavior. Without doing this I believe the distribution of rxqs was dealt with in a round robin manner which could change between deployments. This could explain what you are seeing i.e. sometimes the traffic runs without drops.

You could try to examine ovs-appctl dpif-netdev/pmd-rxq-show when traffic is dropping and then again when traffic is passing without issue. This output along with the flows in each case might provide a clue as to what is happening. If there is a difference between the two you could investigate pinning the rxqs to the specific setup although you will only benefit from this when have at least 2 PMDs instead of 1.

Also OVS 2.6 and DPDK 16.07 aren’t the latest releases of OVS & DPDK, have you tried the same tests using the latest OVS 2.9 and DPDK 17.11?

Ian

From: ovs-discuss-bounces at openvswitch.org [mailto:ovs-discuss-bounces at openvswitch.org] On Behalf Of michael me
Sent: Tuesday, April 17, 2018 10:42 AM
To: ovs-discuss at openvswitch.org
Subject: [ovs-discuss] ovs-dpdk performance not stable

Hi Everyone,

I would greatly appreciate any input.

The setting that i am working with is a host with ovs-dpdk connected to a VM.

What i see when i do performance test is that after about a minute or two suddenly i have many drops as if the cache was full and was dumped improperly.
I tried to play with the settings of the n-rxq and n_txq values, which helps but only probably until the cache is filled and then i have drops.
The things is that sometimes, rarely, as if by chance the performance continues.

My settings is as follows:
OVS Version. 2.6.1
DPDK Version. 16.07.2
NIC Model. Ethernet controller: Intel Corporation Ethernet Connection I354 (rev 03)
pmd-cpu-mask. on core 1 mask=0x2
lcore mask. core zeor "dpdk-lcore-mask=1"

Port "dpdk0"
            Interface "dpdk0"
                type: dpdk
                options: {n_rxq="8", n_rxq_desc="2048", n_txq="9", n_txq_desc="2048"}

ovs-appctl dpif-netdev/pmd-rxq-show
pmd thread numa_id 0 core_id 1:
        isolated : false
        port: dpdk0     queue-id: 0 1 2 3 4 5 6 7
        port: dpdk1     queue-id: 0 1 2 3 4 5 6 7

Thanks,
Michael
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