Software exploitation of traditional interfaces for modern technologies

Abstract

Modern computer Technologies are skyrocketing to spheres, which frequently seemed unimaginable years ago. Quantum effect petabyte-sized storage devices or deep cache hierarchies, acting within nanoseconds, make only a few examples. At the same time, interfaces to communicate with such technologies are settled and remain largely unaffected by the technology development. While loading and storing a word to a given memory address was the standard interface to communicate with memory devices in very early stages of computer systems, it still features a similar shape nowadays. Unsurprisingly, modern computing technologies come with increasing demand of management, such as lifetime management for NON-VOLATILE MEMORY (NVM) or prefetching and eviction strategies for cache hierarchies. Leaving this management to the hardware solely provides a limited design space and space for optimization. Consequently, soft- ware has to find ways, which allow an either direct or indirect management of the technologies over the traditional interfaces. This dissertation picks up this need and studies selected modern technologies and their need for management. Methods are presented in this thesis, which systematically exploit existing traditional interfaces in order to provide extended functionalities for the management of modern technologies. The exploitations in this thesis are solely conducted on a software level and do not require any actions in the available hardware. In a first part, memory technologies are picked up as a target technology. In greater detail, NON-VOLATILE MEMORY (NVM) is studied. This thesis discusses the lifetime issue of these technologies and the resulting need for wear-leveling. Various approaches are introduced, which allow different forms of wear-leveling on different levels of the software. This ranges from wear-leveling procedures inside the operating system and the system software towards direct application integration to extend the memory lifetime. Apart from the lifetime issue, the latency and energy property of a specific type of emerging memory, namely RACETRACK MEMORY (RTM), is considered. Dedicated to the application of RANDOM FOREST (RF) models, the access properties are optimized in the application level directly. In the last part of this thesis, the focus is moved from memories to arithemtic compuation. RANDOM FOREST (RF) models are kept as a target application and their execution on modern computation technologies is considered. The usage of floating- point numbers is put to a major focus and the memory behavior of floating-point numbers is optimized. By proposing alternative computation schemes for floating-point numbers, which are entirely realized in software and leave the hardware untouched, significant performance improvement is gained.