CHARM: Chiplet Heterogeneity-Aware Runtime Mapping System

The growing disparity between CPU core counts and available memory bandwidth has intensified memory contention in servers. This particularly affects highly parallelizable applications, which must achieve efficient cache utilization to maintain performance as CPU core counts grow. Optimizing cache utilization, however, is complex for recent chipletbased CPUs, whose partitioned L3 caches lead to varying latencies and bandwidths, even within a single NUMA domain. Classical NUMA optimizations and task scheduling fail to address the performance issues of chiplet-based CPUs.

We describe Chiplet Heterogeneity Aware Runtime Mapping (CHARM), a new runtime system designed for chipletbased CPUs. CHARM combines chiplet-aware task scheduling heuristics, hardware-aware memory allocation, and fine-grained performance monitoring to optimize workload execution. It implements a lightweight concurrency model that combines user-level threading features, such as individual stacks, per-task scheduling, and state management, with coroutine-like behavior, allowing tasks to suspend and resume execution at defined points while efficiently managing task migration across chiplets. Our evaluation across diverse scenarios shows CHARM's effectiveness in optimizing the performance of memory-intensive parallel applications.