Data Plane Development Kit (DPDK)

I kept noticing that a lot of the carrier OEMs are implementing their "own" Virtual Switches.

I wasn't really sure why, and decided to look into the matter.  After all, there is a fast-performing OpenVSwitch, which while fairly complex, is powerful, flexible, and, well, open source.

Come to learn, there is actually a faster way to do networking than with native OpenVSwitch.

OpenVSwitch minimizes all of the context switching between user space and kernel space when it comes to taking packets from a physical port, and forwarding those packets to virtualized network functions (VNF) and back. 

But - DPDK provides a means to circumvent the kernel, and have practically everything in user space interacting directly to the hardware (bypassing the kernel).

This is fast, indeed, if you can do this. But it bypasses all of the purposes of a kernel network stack, so there has to be some sacrifice (which I need to look into and understand better).  One of the ways it bypasses the kernel is through Direct Memory Access (DMA), based on some limited reading (frankly, reading it and digesting it and understanding it usually requires several reads and a bit of concentration as this stuff gets very complex very fast).

The other question I have, is that if DPDK is bypassing the kernel en route to a physical NIC, what about other kernel-based networking services that are using that same NIC? How does that work?

I've got questions. More questions.

But up to now, I was unaware of this DPDK and its role in the new generation of virtual switches coming out. Even OpenVSwitch itself has a DPDK version.