USENIX Association 2015 USENIX Annual Technical Conference 57 LAMA: Optimized Locality-aware Memory Allocation for Key-value Cache

The in-memory cache system is a performance-critical layer in today’s web server architecture. Memcached is one of the most effective, representative, and prevalent among such systems. An important problem is memory allocation. The default design does not make the best use of the memory. It fails to adapt when the demand changes, a problem known as slab calcification. This paper introduces locality-aware memory alloca-tion (LAMA), which solves the problem by first ana-lyzing the locality of the Memcached requests and then repartitioning the memory to minimize the miss ratio and the average response time. By evaluating LAMA us-ing various industry and academic workloads, the paper shows that LAMA outperforms existing techniques in the steady-state performance, the speed of convergence, and the ability to adapt to request pattern changes and over-come slab calcification. The new solution is close to op-timal, achieving over 98 % of the theoretical potential.