Make Page Coloring more Efficient on Slice-Based Three-Level Cache

Abstract

On modern multi-core machines, page coloring has been used to alleviate the competition at Last Level Cache (LLC). However, the latest development of CPU architecture has brought new issues to page coloring. Firstly, in the case of three-level cache, previous works about page coloring did not discuss the impact on L2 cache of color allocation and the competition for L2 cache is not considered concurrently under hyper-threading. In addition, as the last level cache structure is changed from shared to slice-based and undocumented hash function is applied, page coloring is more complex and slice information is also not fully utilized. This paper presents solutions to these issues. Firstly, by making small changes to the traditional page coloring, the problem that page coloring may waste L2 cache is alleviated. At the same time, we rethink the vertical allocation of L2 cache and LLC in page coloring under hyper-threading, and discuss the impact of color allocation on programs, especially those with different sensitivity to L2 cache and LLC. Finally, we make full use of slice information and propose Partial Conflict Color (PCC). At the same time, we also propose a fast method to obtain PCC. Experiments show that using PCC can improve system performance when the number of colors is insufficient.