PIKA: A Network Service for Multikernel Operating Systems
PIKA is a network stack designed for multikernel operating systems that target potential future architectures lacking cache-coherent shared memory but supporting message passing. PIKA splits the network stack into several servers that communicate using a low-overhead message passing layer. A key challenge faced by PIKA is the maintenance of shared state, such as a single accept queue and load balance information. PIKA addresses this challenge using a speculative 3-way handshake for connection acceptance, and a new distributed load balancing scheme for spreading connections. A PIKA prototype achieves competitive performance, excellent scalability, and low service times under load imbalance on commodity hardware. Finally, we demonstrate that splitting network stack processing by function across separate cores is a net loss on commodity hardware, and we describe conditions under which it may be advantageous.