Computer Science Department
School of Computer Science, Carnegie Mellon University


Data Structure Engineering for High
Performance Software Packet Processing

Dong Zhou

Ph.D. Thesis

August 2019


Keywords: Software Switch, Cuckoo Hashing, Scalability, Network Function Virtualization, Hashing Algorithms

From software routers to virtual swiches to the more general concept of Network Function Virtualization (NFV), the applications of softwarebased packet processing have been booming in recent years. Unlike specialized hardware, general-purpose CPUs are not optimized for processing network packets and thus demand software systems to be carefully designed and optimized to meet ever-increasing performance requirements.

This thesis strives to address the performance challenges of software packet processing by designing and implementing high performance, memory efficient data structures for each of the applications we examined. We make three contributions. First, based on concurrent cuckoo hashing, we propose a set of algorithmic and architecture-aware optimizations to craft an x86-optimized, high-performance hash table, which we then use to build scalable and resource-efficient software-based Ethernet switches. Second, we propose an extremely compact set separation data structure that omits keys and uses a variant of perfect hashing to store values. This data structure is the backbone of our new architecture for building scalable, clustered network appliances. Third, we propose a new software cache design and a cache eviction algorithm that balances between cache hit rate and lookup latency. Replacing the microflow cache in the Open vSwitch with our cache design improves the throughput by up to 15%.

128 pages

Thesis Committee:
David G. Andersen (Chair)
Michael Kaminsky (Intel Labs)
Justine Sherry
Sylvia Ranasamy (University of California at Berkeley)

Srinivasan Seshan, Head, Computer Science Department
Martial Hebert, Dean, School of Computer Science

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