DAOS: Data Access-aware Operating System

Abstract

In data-intensive workloads, data placement and memory management are inherently difficult: the programmer and the operating system have to choose between (combinations of) DRAM and storage, replacement policies, as well as paging sizes. Efficient memory management is based on fine-grained data access patterns driving placement decisions. Current solutions in this space cannot be applied to general workloads and production systems due to either unrealistic assumptions or prohibitive monitoring overheads. To overcome these issues, we introduce DAOS, an open-source system for general data access-aware memory management. DAOS provides a data access monitoring framework that utilizes practical best-effort trade-offs between overhead and accuracy. The memory management engine of DAOS allows users to implement their access-aware management with no code, just simple configuration schemes. For system administrators, DAOS provides a runtime system that auto-tunes the schemes for user-defined objectives in a finite time. We evaluated DAOS on commercial service production systems as well as state-of-the-art benchmarks. DAOS achieves up to 12% performance improvement and 91% memory saving. DAOS is upstreamed and available in the Linux kernel.