DPDK Archives - NielsHagoort.com

The VMkernel is relying on the physical device, the pNIC in this case, to generate interrupts to process network I/O. This traditional style of I/O processing incurs additional delays on the entire data path from the pNIC all the way up to within guest OS. Processing I/Os using interrupt based mechanisms allows for CPU saving because multiple I/Os are combined in one interrupt. Using poll mode, the driver and the application running in the guest OS will constantly spin waiting for an I/O to be available. This way, an application can process the I/O almost instantly instead of waiting for an interrupt to occur. That will allow for lower latency and a higher Packet Per Second (PPS) rate.

An interesting fact is that the world is moving towards poll-mode drivers. A clear example of this is the NVMe driver stack.

The main drawback is that the poll-mode approach consumes much more CPU time because of the constant polling for I/O and the immediate processing. Basically, it consumes all the CPU you offer the vCPUs used for polling. Therefore, it is primarily useful when the workloads running on your VMs are extremely latency sensitive. It is a perfect fit for data plane telecom applications like a Packet GateWay (PGW) node as part of a Evolved Packet Core (EPC) in a NFV environment or other real-time latency sensitive workloads.

Using the poll-mode approach, you will need a pollmode driver in your application which polls a specific device queue for I/O. From a networking perspective, Intel’s Data Plane Development Kit (DPDK) delivers just that. You could say that the DPDK framework is a set of libraries and drivers to allow for fast network packet processing.

Data Plane Development Kit (DPDK) greatly boosts packet processingperformance and throughput, allowing more time for data plane applications. DPDK can improve packet processing performance by up to ten times. DPDK software running on current generation Intel®Xeon® Processor E5-2658 v4, achieves 233 Gbps (347 Mpps) of LLC forwarding at 64-byte packet sizes. Source: http://www.intel.com/content/www/us/en/communications/data-planedevelopment-kit.html

DPDK in a VM

Using a VM with a VMXNET3 network adapter, you already have the default paravirtual network connectivity in place. The following diagram shows the default logical paravirtual device connectivity.

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In my current role, I am involved in a lot of discussions around network functions virtualization, a.k.a. NFV. Talking about NFV in this post, I mean telco applications. By that I mean applications specifically designed for and used by Communications Service Providers (CSPs) as core applications to, for instance, enable your (mobile) phone to actually be able to call another phone. 🙂

NFV with regards to telco applications is not that mainstream so it seems. The old school native way, having telco specific hardware running line cards, payload servers, etc., obviously is not sustainable looking at the current way we like to do ICT. On the other hand, it looks like telco application vendors are still finding their way on how to properly adopt virtualization as a technology. So it looks like the level of virtualization adoption for network functions is a few years back in comparison to IT application server virtualization.

But development is rapid, and so it is for NFV. There already is a NFV Architecture Framework created by ETSI. ETSI was selected in November 2012 to be the home of the Industry Specification Group for NFV. The framework is a high-level functional architecture and design philosophy for virtualized network functions and the underlying virtualization infrastructure as shown in the following diagram:

Although there are words that NFV is mostly deployed using a KVM hypervisor working closely with OpenStack as the API framework for NFV, VMware is looking to hook into the needs of the communications service providers to properly ‘do’ NFV using VMware solutions. Hence the vCloud for NFV suite.

VMware vCloud NFV is a Network Functions Virtualization (NFV) services delivery, operations and management platform, developed for Communications Service Providers (CSPs) who want to reduce infrastructure CapEx and OpEx costs, improve operational agility and monetize new services with rapid time to market.

Let’s have a closer look at tuning considerations for vSphere to properly run NFV workloads!
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DPDK

Virtual Networking: Poll-mode vs Interrupt

DPDK in a VM

vSphere and NFV tuning considerations