Non-Intrusive and Workflow-Aware Virtual Network Function Scheduling in User-Space

The simple programming model and very low-overhead I/O capabilities of emerging packet processing techniques leveraging kernel-bypass I/O and poll-mode processing is gaining significant popularity for building high performance software
middleboxes
(
aka

Virtual Network Functions (VNFs)
). However, existing OS schedulers fall short in rightsizing CPU allocation to poll-mode VNFs due to the schedulers’ shortcoming in capturing the actual processing cost of these VNFs. This issue is further exacerbated by their inability to consider VNF processing order when VNFs are chained to form Service Function Chains (SFCs). The state-of-the-art VNF schedulers proposed as an alternative to OS schedulers are
intrusive
, requiring the VNFs to be built with scheduler specific libraries or having carefully selected scheduling checkpoints. This highly restricts the VNFs that can properly work with these schedulers. In this article, we present
UN
i
S
, a
U
ser-space
N
on-
i
ntrusive work-flow aware VNF
S
cheduler. Unlike existing approaches, UNiS is non-intrusive, i.e., does not require VNF modifications and treats poll-mode VNFs as black boxes. UNiS is also workflow-aware, i.e., takes SFC processing order into account while scheduling VNFs. Testbed experiments show that
UN
i
S
is able to achieve a throughput within 90 and 98 percent of that achievable using an intrusive co-operative scheduler for synthetic and real data center traffic, respectively.