Poseidon-Firmament Scheduler – Flow Network Graph Based Scheduler

In this blog post, we briefly describe the novel Firmament flow network graph based scheduling approach (OSDI paper) in Kubernetes. We specifically describe the Firmament Scheduler and how it integrates with the Kubernetes cluster manager using Poseidon as the integration glue. We have seen extremely impressive scheduling throughput performance benchmarking numbers with this novel scheduling approach.

Originally, Firmament Scheduler was conceptualized, designed and implemented by University of Cambridge researchers, Malte Schwarzkopf & Ionel Gog. At a very high level, Poseidon-Firmament scheduler augments the current Kubernetes scheduling capabilities by incorporating novel flow network graph based scheduling capabilities alongside the default Kubernetes Scheduler. It models the scheduling problem as a constraint-based optimization over a flow network graph – by reducing scheduling to a min-cost max-flow optimization problem.

Due to the inherent rescheduling capabilities, the new scheduler enables a globally optimal scheduling environment that constantly keeps refining the workloads placements dynamically.

Source: kubernetes.io