A Software Cache Partitioning System for Hash-Based Caches

Abstract

Contention on the shared Last-Level Cache (LLC) can have a fundamental negative impact on the performance of applications executed on modern multicores. An interesting software approach to address LLC contention issues is based on page coloring , which is a software technique that attempts to achieve performance isolation by partitioning a shared cache through careful memory management. The key assumption of traditional page coloring is that the cache is physically addressed. However, recent multicore architectures (e.g., Intel Sandy Bridge and later) switched from a physical addressing scheme to a more complex scheme that involves a hash function. Traditional page coloring is ineffective on these recent architectures. In this article, we extend page coloring to work on these recent architectures by proposing a mechanism able to handle their hash-based LLC addressing scheme. Just as for traditional page coloring, the goal of this new mechanism is to deliver performance isolation by avoiding contention on the LLC, thus enabling predictable performance. We implement this mechanism in the Linux kernel, and evaluate it using several benchmarks from the SPEC CPU2006 and PARSEC 3.0 suites. Our results show that our solution is able to deliver performance isolation to concurrently running applications by enforcing partitioning of a Sandy Bridge LLC, which traditional page coloring techniques are not able to handle.