Programmable packet scheduling enables the integration of scheduling algorithms into switches without the need for hardware redesign. The Push-In First-Out (PIFO) queue facilitates a programmable packet scheduler, supporting a single scheduling algorithm flexibly. However, hierarchical scheduling required in Multi-Tenant Data Centers (MTDCs) remains non-programmable. Dynamic and diverse hierarchical scheduling algorithms necessitate alterations in both the number of PIFO queues and their connection topology, posing a significant challenge to support them on fixed hardware.

Push-In-First-Out (PIFO) queue has been extensively studied as a programmable scheduler. To achieve accurate, large-scale, and high-throughput PIFO implementation, we propose the Balanced Multi-way (BMW) Sorting Tree for real-time packet sorting. The tree is highly modularized, insertion-balanced and pipeline-friendly with autonomous nodes.