Hello,
SR-IOV & VMQ perform a similar functions in a different ways.
VMQ:
With VMDq, the VM manager can assign a separate queue in the network adapter to each VM, which removes overhead on the virtual switch sorting and routing for where the packets need to go. However, the VM manager and the virtual switch still have to copy the traffic from the VMDq to the VM, which, for Hyper-V, travels over the kernel-mode memory bus.
Additionally, because there are multiple queues, the incoming load can be spread over multiple processor cores removing any potential processing bottleneck. VMDq reduces the work on the virtual switch and enables better scalability, but the traffic still flows through the virtual switch and over normal data transports (VMBus)
SR-IOV:
SR-IOV works similarly to VMDq, but instead of creating a separate queue for each VM, it actually creates a separate Virtual Function (VF) that acts like a separate network device for each VM. The VM communicates directly with it, completely bypassing the virtual switch and any load-copying data on the VM manager, since SR-IOV uses Direct Memory Accesss (DMA) between the VF and the VM.
SR-IOV offers the best network performance but requires support on the hypervisor, motherboard, and network adapter and might affect portability of VMs between hardware capable of using SR-IOV and hardware incapable of using SR-IOV.
QI. 've noticed enabling SR-IOV on these adapters that I lose all the NumberOfReceiveQueues. Is this normal or should there still receive queues if SR-IOV is enabled in Virtual Connect and the bios? The servers are BL460c Gen8 and Gen9 with FlexFabric modules in a c7000
A.SR-IOV allows each VM to have direct access to packets queued up for the VFs attached to the VM. When SR-IOV is disabled, the host creates a single PF on one physical NIC & is normal.
Regards,
HPE Employee
