Energy-aware assignment and scheduling for hybrid main memory in embedded systems

Abstract

In embedded systems, especially battery-driven mobile devices, energy is one of the most critical performance metrics. Due to its high density and low standby power, phase change memory (PCM), an emerging non-volatile memory device, is becoming a promising dynamic random access memory (DRAM) alternative. Recent studies have proposed the hybrid main memory architecture integrating both PCM and DRAM to fully take advantage of the properties of both memories. However, the low power performance of PCM in the hybrid main memory architecture has not been fully explored. Therefore, it becomes an interesting problem to utilize PCM and DRAM as hybrid main memory for energy optimization in embedded systems. In this paper, we present an energy optimization technique for hybrid main memory architecture. The objective is to fully utilize PCM to reduce the energy consumption while ensuring that the real-time performance of applications are guaranteed. We propose a two-phase approach to solve hybrid main memory address mapping problem. In the first phase, we calculate energy and time cost for each address based on the task models. Then the applications can be modeled as data-flow graph nodes, and different access times will associate with different energy consumption. In the second phase, for different memory types and the given timing constraint, we formulate the scheduling problem as an integer linear programming (ILP) model and obtain an optimal solution. The 123 G. Wang et al.ILP model can map a proper memory type for each address such that the total energy consumption can be minimized while the timing constraint is satisfied. In addition, we propose a heuristic approach to efficiently obtain a near-optimal solution. We conduct experiments on an ARM-based simulator. The experimental results show that our method can effectively reduce the energy consumption with the least system cost compared with the previous work.

Dynamics of information diffusion and its applications on complex networks

“…For example, for new technologies to reach 50 million users, it took 50 years for electricity, while MySpace used only one year. Online social media also enable researchers and the industry to quantify factors that may be crucial to innovation diffusion besides characters of the innovation itself, such as opinion leaders, network local clustering [64,67,72,73].…”

A Survey of Hybrid Main Memory Architectures

“…In the remainder of this section, we tried to examine some selected solutions, which include different hybrid main memory architecture models given in works listed on Table 1. [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26] 2 DRAM + PRAM [27], [28], [29], [30], [31], [32], [33], [34], [35], [36] 3 DRAM + NVM [37], [38], [39], [40], [41] 4…”

“…Figure 13: SLC/MLC PRAM + DRAM main memory [35] For the sake of energy optimization of the PCM and DRAM combined main memory structure shown in Fig. 14, Wang and colleagues aimed to use the PCM completely to ensure the performance of real-time applications and reduce energy consumption [22]. This study proposed an optimal address-mapping algorithm for mapping an appropriate memory address for each address.…”

“…They concluded that the introduced approach could meaningly decrease energy consumption at the minimum cost when analyzed by the conventional techniques [22]. Figure 14: Hybrid DRAM/PCM memory in embedded system [22] For real-time task-timeline problem for energy efficiency, [23] introduced static table-based and dynamic time lining algorithms for an extraordinary set of tasks. They also introduced 4 real-time programming algorithms based on RM (Rate-Monotonic) and EDF (Earliest Deadline First) timers for real-time embedded systems with a combined PCM-DRAM main memory (in Fig.…”

NVMRA: utilizing NVM to improve the random write operations for NAND-flash-based mobile devices

“…Compared with flash memory, newly emerged NVM, such as phase-change memory (PCM), can well overcome the previous constrains. NVM has high I/O performance, low standby power, and in-place update features [29][30][31][32][33][34]. All these features make PCM as a promising solution to effectively improve the I/O performance for NAND flash memory, and thus enhance the performance of applications.…”