Carbon-Aware Memory Placement

The carbon footprint of software activities is determined by embodied and operational emissions of hardware resources. This paper presents cMemento, a concept that enables operating systems to make carbon-aware memory placement decisions. Main memory has become heterogeneous in today's computer systems. In addition to traditional (and volatile) main memory (e.g. DRAM), novel memory technologies with persistent properties are often also available (e.g. PRAM, FRAM, MRAM). Complementary, there are a large number of new memory interfaces (e.g. high-bandwidth, graphics, and low-power memory) that have to be additionally taken into account by the operating system when allocating memory. The availability of new memory technologies and interfaces enables systems with improved energy efficiency. At the same time, the new memory interfaces have revealed serious flaws in the current state-of-the-art memory abstractions in operating systems. Hence, moving away from the homogeneous perspective of memory resources is a crucial step towards significantly reducing the energy consumption and, ultimately, the carbon footprint of today's computer systems. With cMemento, we propose an approach that combines information on characteristics of (i) active workloads and (ii) available memory resources with a carbon model. cMemento transforms the combined information into memory placement decisions at operating system level. The placement decisions that are made result in improved operating conditions (i.e. better energy efficiency and lower carbon footprint) for the available memory resources.