[dpdk-dev] RSS, performance, and stability issues vmxnet3-pmd

Daniel Kan dan at nyansa.com
Tue Mar 11 20:55:05 CET 2014

I’m unable to get RSS to work properly with vmxnet3-pmd. The first issue is that the number of rxqs must be power of 2. Otherwise, rte_eth_dev_start() fails due to inability to activate vmxnet3 NIC. This is not too big of a deal, but physical NICs don’t have this requirement. 

The second issue is that RSS is just not working at all for me. The rxmode is set to ETH_MQ_RX_RSS and rss_hf = ETH_RSS_IPV4_TCP | ETH_RSS_IPV4_UDP | ETH_RSS_IPV4 | ETH_RSS_IPV6. The same configuration works for a real NIC. When I checked mb->pkt.hash, the value is all zeroed out. 

Even if I disabled RSS, I found the performance of vmxnet3-pmd to be quite poor, peaking out at 600k pps with 64 byte packet, while libpcap can do 650k pps. 

Lastly, there is a stability issue. On a number of occasions, vmxnet3-pmd stops receiving packets after some random time and several million packets. 

I’m not sure if anyone else is having as much issue as I’m, I will give vmxnet3-usermap a try. 

Finally, does either vmxnet3-usermap or vmxnet3-pmd work well for non-Intel-based underlying physical NIC? 



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