Thanks Keith for your reply I found out that the bottleneck are the VMs and not the OVS/OVS-DPDK running in the host. VMs on both setup are unaware to OVS/OVS-DPDK and use their linux IP-stack. I found that the performance (e.g. throughput) between VMa - OVS-DPDK - network - OVS-DPDK - VMb is much better than with standard OVS.
I use vhost-user virtio for the OVS-DPDK setup to connect to VM , and vhost-net for the standard OVS The reasons for standard OVS poor performance can be for example: 1. number of packet copies in the path NIC - OVS - OS-guest-virtio - Application on guest 2. interrupt upon receiving a packet 3. # of context-switch / VM-exit etc.. I didn't see any info regarding these potential reasons on the docs. Best Regards avi > -----Original Message----- > From: Wiles, Keith [mailto:[email protected]] > Sent: Wednesday, 24 May, 2017 4:23 PM > To: Avi Cohen (A) > Cc: [email protected] > Subject: Re: [dpdk-users] OVS vs OVS-DPDK > > > > On May 24, 2017, at 3:29 AM, Avi Cohen (A) <[email protected]> > wrote: > > > > Hello > > Let me ask it in a different way: > > I want to understand the reasons for the differences in performance between > OVS-DPDK and standard OVS My setup is: ovs/ovs-dpdk is running @ host > communicating with a VM > > > > OVS-DPDK > > 1. packet is received via physical port to the device. > > > > 2.DMA transfer to mempools on huge-pages allocated by dpdk-ovs - in > user-space. > > > > 3. OVS-DPDK copies this packet to the shared-vring of the associated guest > (shared between ovs-dpdk userspace process and guest) > > > > 4. guest OS copies the packet to userspace application on VM . > > > > Standard OVS > > > > 1. packet is received via physical port to the device. > > > > 2.packet is processed by the OVS and transferred to a virtio device > > connected > to the VM - whar are the additional overhead here ? QEMU processing - > translation , VM exit ?? other ? > > > > 3. guest OS copies the packet to userspace application on VM . > > > > > > Question: what are the additional overhead in the standard OVS that cause > to poor performance related to the OVS-DPDK setup ? > > I'm not talking about the PMD improvements (OVS-DPDK) running on the > host - but on overhead in the VM context in the standard OVS setup > > The primary reasons are OVS is not using DPDK and OVS is using the Linux > kernel as well :-) > > > > > Best Regards > > avi > > Regards, > Keith
