FACRA: Flexible-Core Architecture Chip Resource Abstractor

A family of flexible-core chip multiprocessors (FCMPs) has been recently proposed to allow simple, identical physical cores to be aggregated dynamically to form larger and more powerful logical processors. However, such flexible-core architecture faces a new significant scheduling problem in the operating system, which traditionally assumes only fixed-number and fixed-granularity processors. This paper proposes a framework, called FACRA, that employs low-level runtime software to simplify OS resource allocation and process scheduling on FCMPs. Through exporting a simple, uniform processor abstraction on flexible-core chip resource, FACRA provides a set of functions with uniform interface for system-level scheduling on FCMPs. To verify the design, FACRA is built on TFlex (a typical FCMP) in our experiments, and two well known process schedulers, round-robin and dynamic-priority scheduler of Linux 2.6.11, are modified to schedule on TFlex. The evaluation results demonstrate that FACRA can efficiently simplify OS resource allocation and process scheduling on FCMPs with negligible performance loss.