5G is designed to be a multi-service network, capable of supporting diverse range of applications with distinct quality of service (QoS) requirements. Network slicing is one of the key technologies that will enable differentiated service provision on 5G networks, realized using multi-access edge computing (MEC), network function virtualization (NFV), and software-defined networking (SDN). It allows the network operators to build multiple virtual networks over a shared infrastructure, thereby providing network as a service for different service classes. MEC plays a key role in network-slicing based 5G architecture, as it can be used to support virtual network functions for core network (CN) and radio access network (RAN) for latency sensitive applications. Each MEC server can be considered as a pool of virtualized resources running on standard hardware infrastructure. Although network slicing is a promising technology, it still has many challenges that need to be addressed for effective service provisioning. In this work, we focus on challenges related to MEC for supporting network slicing for QoS provisioning in different 5G use cases, and discuss how operating system (OS) level optimizations can help to overcome them.