This ticket is created automatically to track an investigation spike related to the issue: FDP-1572.

The goal is to identify the root cause or clarify unknowns and evaluate possible solutions or workarounds for the problem described below.

 Problem Description: Clearly explain the issue.

cx6 lx card: some ovs dpdk pvp perf test got low performance
 

 Impact Assessment: Describe the severity and impact (e.g., network down,availability of a workaround, etc.).

 Software Versions: Specify the exact versions in use (e.g.,openvswitch3.1-3.1.0-147.el8fdp).

openvswitch3.5-3.5.1-42.el9fdp
 openvswitch3.5-3.5.0-13.el10fdp

  Issue Type: Indicate whether this is a new issue or a regression (if a regression, state the last known working version).

 Reproducibility: Confirm if the issue can be reproduced consistently. If not, describe how often it occurs.

 Reproduction Steps: Provide detailed steps or scripts to replicate the issue.

Run ovs dpdk pvp perf test job
build ovs dpdk bridge
add two dpdk port to ovs bridge
add two vhostuser port to ovs bridge
inside guest, start testpmd forward packet
On trex side, send rfc2544 traffic.
 

 Expected Behavior: Describe what should happen under normal circumstances.

All cases got normal performance
 

 Observed Behavior: Explain what actually happens.

some cases got low performance, such following job of openvswitch3.5-3.5.1-42.el9fdp.
ovs_dpdk_vhostuser_pvp_queues1_pmds2_vcpus3_vIOMMU_no_vlan1 1500byte got 1.0mpps, it should got about 1.8mpps

ovs_dpdk_vhostuser_pvp_queues1_pmds4_vcpus3_vIOMMU_no_vlan11 1500byte got 1.0mpps, it should got about 2.8mpps

ovs_dpdk_vhostuser_pvp_queues4_pmds8_vcpus9_vIOMMU_yes_vlan0 256byte got 5.6mpps, it should got about 16mpps

ovs_dpdk_vhostuser_pvp_queues1_pmds2_vcpus3_vIOMMU_no_vlan11 2000byte got 0.754mpps, it should got about 1.4mpps

https://beaker.engineering.redhat.com/jobs/11476613
https://beaker-archive.prod.engineering.redhat.com/beaker-logs/2025/08/114766/11476613/19263898/199015352/mlx5_25.html
 

For following job of openvswitch3.5-3.5.0-13.el10fdp
ovs_dpdk_vhostuser_pvp_queues1_pmds4_vcpus3_vIOMMU_yes_vlan0 1500byte got 1.0mpps, it should got about 3mpps

ovs_dpdk_vhostuser_pvp_queues1_pmds2_vcpus3_vIOMMU_no_vlan11 2000byte got 0.775mpps, it should got about 1.4mpps

https://beaker.engineering.redhat.com/jobs/10997971
https://beaker-archive.prod.engineering.redhat.com/beaker-logs/2025/04/109979/10997971/18600649/194311958/mlx5_25.html

For ovs3.4 and ovs3.3, it has no issue.
ovs3.3:
https://beaker.engineering.redhat.com/jobs/10988728
https://beaker-archive.prod.engineering.redhat.com/beaker-logs/2025/04/109887/10988728/18585889/194183083/mlx5_25.html
ovs3.4
https://beaker.engineering.redhat.com/jobs/10993817
https://beaker-archive.prod.engineering.redhat.com/beaker-logs/2025/04/109938/10993817/18594096/194253692/mlx5_25.html

There is no this issue for cx6 dx card.

 Troubleshooting Actions: Outline the steps taken to diagnose or resolve the issue so far.

 Logs: If you collected logs please provide them (e.g. sos report, /var/log/openvswitch/* , testpmd console)

https://beaker-archive.prod.engineering.redhat.com/beaker-logs/2025/08/114766/11476613/19263897/199015350/ovs-vswitchd.log