Hash Table Scalability on Intel PIUMA

The Intel PIUMA (Programmable and Integrated Unified Memory Architecture) is a scalable, massively multithreaded architecture designed to operate on unstructured data, with a global address space, fine-grain memory access and various novel features for latency hiding during data movement. Hash tables are a commonly used data structure with unstructured data, hence it is imperative that the performance and scaling for hash table usages are optimized for this architecture. We study three different hash table implementations on a PIUMA simulator to show that a dual-atomics based implementation, a unique feature in PIUMA, performs competitively both at larger scales and under hash collisions. Our implementations are able to achieve strong scaling up to 16,384 hardware threads.