RISO: Enforce Noninterfered Performance With Relaxed Network-on-Chip Isolation in Many-Core Cloud Processors

Workload consolidation is widely used in modern cloud processors to reduce total cost of ownership. Performance isolation has to be enforced between consolidated workloads to achieve controllable quality of service. Networks-on-chip (NoCs), as a major shared resource, often incur traffic interference and violate performance isolation criteria. Previous work resorts to strict isolation strategy that partitions NoC into independent regions to isolate core-to-core communication traffic. However, strict isolation either results in low consolidation density or degrades network performance, and more importantly, cannot be applied to memory access traffic. To address these weaknesses, we propose a novel performance isolation strategy in NoC, called relaxed isolation (RISO). It permits underutilized routers and links to be shared by multiple applications, and, at the same time, it keeps the aggregated traffic in check to enforce performance isolation. Experimental results show that RISO could effectively improve consolidation density and network performance in synergy.