Are you sure the anonhugepages size was equal to the total VM's memory size? Sometimes, transparent huge page mechanism doesn't grantee the app is using the real huge pages.
-----Original Message----- From: users [mailto:[email protected]] On Behalf Of edgar helmut Sent: Thursday, December 15, 2016 9:32 PM To: Wiles, Keith Cc: [email protected] Subject: Re: [dpdk-users] Dpdk poor performance on virtual machine I have one single socket which is Intel(R) Xeon(R) CPU E5-2640 v4 @ 2.40GHz. I just made two more steps: 1. setting iommu=pt for better usage of the igb_uio 2. using taskset and isolcpu so now it looks like the relevant dpdk cores use dedicated cores. It improved the performance though I still see significant difference between the vm and the host which I can't fully explain. any further idea? Regards, Edgar On Thu, Dec 15, 2016 at 2:54 PM, Wiles, Keith <[email protected]> wrote: > > > On Dec 15, 2016, at 1:20 AM, edgar helmut <[email protected]> > 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 > >
