[dpdk-users] Dpdk poor performance on virtual machine

[Wiles, Keith]

> On Dec 15, 2016, at 1:20 AM, edgar helmut <helmut.edgar100 at gmail.com> wrote:
> 
> Hi.
> Some help is needed to understand performance issue on virtual machine.
> 
> Running testpmd over the host functions well (testpmd forwards 10g between
> two 82599 ports).
> However same application running on a virtual machine over same host
> results with huge degradation in performance.
> The testpmd then is not even able to read 100mbps from nic without drops,
> and from a profile i made it looks like a dpdk application runs more than
> 10 times slower than over host…

Not sure I understand the overall setup, but did you make sure the NIC/PCI bus is on the same socket as the VM. If you have multiple sockets on your platform. If you have to access the NIC across the QPI it could explain some of the performance drop. Not sure that much drop is this problem.

> 
> Setup is ubuntu 16.04 for host and ubuntu 14.04 for guest.
> Qemu is 2.3.0 (though I tried with a newer as well).
> NICs are connected to guest using pci passthrough, and guest's cpu is set
> as passthrough (same as host).
> On guest start the host allocates transparent hugepages (AnonHugePages) so
> i assume the guest memory is backed with real hugepages on the host.
> I tried binding with igb_uio and with uio_pci_generic but both results with
> same performance.
> 
> Due to the performance difference i guess i miss something.
> 
> Please advise what may i miss here?
> Is this a native penalty of qemu??
> 
> Thanks
> Edgar

Regards,
Keith