[ovs-dev] vhost-user invalid txqid cause discard of packets

Wang, Zhihong zhihong.wang at intel.com
Thu Mar 3 15:24:13 UTC 2016


Hi,

I ran an OVS multiqueue test with very simple traffic topology, basically
2 ports each with 4 queues, 8 rxqs in total, like below:

Pktgen <=4q=> PHY <=4q=> OVS <=4q=> testpmd in the guest

First set pmd-cpu-mask to 8 cores, and everything works fine, each rxq
got a core, and all txqids are valid.

Then I set pmd-cpu-mask to 6 cores, and then 2 txqids become invalid in
__netdev_dpdk_vhost_send():
qid = vhost_dev->tx_q[qid % vhost_dev->real_n_txq].map;

qid returns -1 and this leads to discard of packets.

Consequently in testpmd in VM we see only 2 queues are working and
throughput drops more than a half.

It works again when I set pmd-cpu-mask to 4 cores.

My OVS and DPDK code are pulled from the repo on March 1st, 2016.

Let me know if you need more info to reproduce this issue.


Thanks
Zhihong



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