A bounded memory allocator for software-defined global address spaces

International audienceThis paper presents a memory allocator targeting manycore architectures with distributed memory.Among the family of Multi Processor System on Chip (MPSoC), these devices are composed of multiple nodes linked by an on-chip network; most nodes have multiple processors sharing a small local memory. While MPSoC typically excel on their performance-per-Watt ratio, they remain hard to program due to multilevel parallelism, explicit resource and memory management, and hardware constraints (limited memory, network topology).Typical programming frameworks for MPSoC leave much target-specific work to the programmer: combining threads or node-local OpenMP, software caching, explicit message passing (and sometimes, routing), with non-standard interfaces. More abstract, automatic frameworks exist, but they target large-scale clusters and do not model the hardware constraints of MPSoC.The memory allocator described in this paper is one component of a larger runtime system, called Givy, to support dynamic task graphs with automatic software caching and data-driven execution on MPSoC.To simplify the programmer's view of memory, both runtime and program data objects live in a Global Address Space (GAS).To avoid address collisions when objects are dynamically allocated, and to manage virtual memory mappings across nodes, a GAS-aware memory allocator is required.This paper proposes such an allocator with the following properties:(1) it is free of inter-node synchronizations;(2) its node-local performance match that of state-of-the-art shared-memory allocators;(3) it provides node-local mechanisms to implement inter-node software caching within a GAS;(4) it is well suited for small memory systems (a few MB per node)