Hi, I considered that the reason why the outlier (such as, 120-200 or 200-400) for Hi Pri PTP is observed with 120% tput.
There are two estimation for the outlier. The first one is VM scheduling latency. In this experiment, the VM is used for the measurement. The results would be different due to the number of VMs on node. If there are many VMs on the node and it suffers a lack of CPU resource, the scheduling latency will be increased and it would be a major cause of the outlier. Did you confirm the number of VMs in the experiment ? The next one is the packet processing delay of testpmd. In my understanding, testpmd is user process on VM. Although pmd thread forwards packets to testpmd as soon as possible, the context switching of testpmd would be occurred by kernel. As a result, testpmd cannot process the packets from the pmd thread as soon as possible. Please let me confirm the experiment condition without baseline again. In the priority path, is there no queue for Hi Pri PTP? Thus, there is only one designated queue for Lo Pri2. The traffic of Lo Pri2 is en/dequeued on the designated queue. There is no special function on DPDK OVS switch to process the traffic Hi Pri PTP. Is it right ? Regards, Chunghan Lee
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