id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host 11154,Bad VM to Host Network Performance with Intel NIC or virtio,Gevatter Gaul,,"I'm running VirtualBox 4.2 on a Ubuntu 12.04 LTS 64bit. The machine is a Xeon E1230 Quadcore with 32G ECC RAM. The VM, running Ubuntu 12.04 LTS 64bit, is connected via a Host Adapter. When running a ping from the Host to the VM, everything seems fine and I get an average latency of around 0.2ms. But in the other direction, depending on the configured VM NIC, I get very high ping results. Strangely enough, the problem only exists, when configuring more than one virtual CPU. Here are my measurements: Average Ping: VCPUs PCnet-PCI II PCnet-FAST III Intel PRO/1000 MT Desktop Intel PRO/1000 T Server Intel PRO/1000 MT Server Paravirtualized Network 1 0.168 0.183 0.209 0.191 0.206 0.399 2 0.193 0.182 15.987 12.157 10.349 5.327 3 0.179 0.167 12.032 14.052 9.657 5.337 4 0.174 0.176 12.929 13.680 13.627 5.482 mdev: VCPUs PCnet-PCI II PCnet-FAST III Intel PRO/1000 MT Desktop Intel PRO/1000 T Server Intel PRO/1000 MT Server Paravirtualized Network 1 0.043 0.046 0.040 0.061 0.039 0.055 2 0.085 0.085 16.036 16.390 14.946 4.638 3 0.045 0.046 14.575 16.903 13.330 5.252 4 0.045 0.044 16.286 16.033 16.148 4.881 We see, as soon as I configure more than one VCPU, latency goes through the roof. vbox guest log and showvminfo output are attached.",defect,closed,network/hostif,VirtualBox 4.2.4,duplicate,nic intel ping latency bug performance,,Linux,Linux