Dynamic Frequency Clocking Research Articles

Exploration of the Power-Performance Tradeoff through Parameterization of FPGA-Based Multiprocessor Systems

The design space of FPGA-based processor systems is huge, because many parameters can be modified at design- and runtime to achieve an efficient system solution in terms of performance, power and energy consumption. Such parameters are, for example, the number of processors and their configurations, the clock frequencies at design time, the use of dynamic frequency scaling at runtime, the application task distribution, and the FPGA type and size. The major contribution of this paper is the exploration of all these parameters and their impact on performance, power dissipation, and energy consumption for four different application scenarios. The goal is to introduce a first approach for a developer's guideline, supporting the choice of an optimized and specific system parameterization for a target application on FPGA-based multiprocessor systems-on-chip. The FPGAs used for these explorations were Xilinx Virtex-4 and Xilinx Virtex-5. The performance results were measured on the FPGA while the power consumption was estimated using the Xilinx XPower Analyzer tool. Finally, a novel runtime adaptive multiprocessor architecture for dynamic clock frequency scaling is introduced and used for the performance, power and energy consumption evaluations.

A scheduling scheme with Dynamic Frequency Clocking and multiple voltages for low power designs

In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints. Unlike the conventional methods at high level synthesis where only voltages of nodes were considered, the scheme based on a gain function considers both voltage and frequency simultaneously to reduce energy consumption. Experiments with a number of DSP benchmarks show that the proposed scheme achieves an effective energy reduction.

ILP models for simultaneous energy and transient power minimization during behavioral synthesis

In low-power design for battery-driven portable applications, the reduction of peak power, peak power differential, cycle difference power, average power and energy are equally important. These are different forms of dynamic power dissipation of a CMOS circuit, which is predominant compared to static power dissipation for higher switching activity. The peak power, the cycle difference power, and the peak power differential drive the transient characteristic of a CMOS circuit. In this article, we propose an ILP-based framework for the reduction of energy and transient power through datapath scheduling during behavioral synthesis. A new metric called “modified cycle power function” (CPF*) is defined that captures the above power characteristics and facilitates integer linear programming formulations. The ILP-based datapath scheduling schemes with CPF* as objective function are developed assuming three modes of datapath operation, such as, single supply voltage and single frequency (SVSF), multiple supply voltages and dynamic frequency clocking (MVDFC), and multiple supply voltages and multicycling (MVMC). We conducted experiments on selected high-level synthesis benchmark circuits for various resource constraints and estimated power, energy and energy delay product for each of them. Experimental results show that significant reductions in power, energy and energy delay product can be obtained.

Simultaneous peak and average power minimization during datapath scheduling

In low-power design for deep submicrometer and nanometer regimes, peak power, power fluctuation, average power, and total energy are equally important design constraints. In this paper, we propose datapath scheduling algorithms for simultaneous minimization of peak and average power. The minimization schemes based on integer linear programming are developed for the design of datapaths that can function in three modes of operation: 1) single supply voltage and single frequency; 2) multiple supply voltages and dynamic frequency clocking (MVDFC); and 3) multiple supply voltages and multicycling. The techniques are evaluated by estimating the peak power consumption, the average power consumption and the power delay product of selected high level synthesis benchmark circuits for different resource constraints. Experimental results indicate that combining multiple voltages and dynamic frequency clocking as in the MVDFC scheme, yields significant reductions in the peak power, the average power, and the power delay product.

Energy-efficient datapath scheduling using multiple voltages and dynamic clocking

Recently, dynamic frequency scaling has been explored at the CPU and system levels for power optimization. Low-power datapath scheduling using multiple supply voltages has been well researched. In this work, we develop new datapath scheduling algorithms that use multiple supply voltages and dynamic frequency clocking in a coordinated manner in order to reduce the energy consumption of datapath circuits. In dynamic frequency clocking, the functional units can be operated at different frequencies depending on the computations occurring within the datapath during a given clock cycle. The strategy is to schedule high-energy units, such as multipliers at lower frequencies, so that they can be operated at lower voltages to reduce energy consumption and the low-energy units, such as adders at higher frequencies, to compensate for speed. The proposed time- and resource-constrained algorithms have been applied to various high-level synthesis benchmark circuits under different time and resource constraints. The experimental results show significant reduction in energy for both the algorithms.

A framework for energy and transient power reduction during behavioral synthesis

In battery driven portable applications, the minimization of energy, average power, peak power, and peak power differential are equally important to improve reliability and efficiency. The peak power and the peak power differential drive the transient characteristics of a CMOS circuit. In this paper, we propose a framework for the simultaneous reduction of energy and transient power during behavioral synthesis. A new metric called "cycle power function" (CPF) is defined which captures the transient power characteristics as an equally weighted sum of the normalized mean cycle power and the normalized mean cycle differential power. Minimizing CPF using multiple supply voltages and dynamic frequency clocking under resource constraints results in the reduction of both energy and transient power. Based on the above, we develop a new datapath scheduling algorithm called CPF-scheduler which attempts at power and energy minimization by minimizing the CPF parameter during the scheduling process. The type and number of functional units available become the set of resource constraints for the scheduler. Experimental results indicate that the proposed scheduler achieves significant reductions in terms of power and energy.

A linear array processor with dynamic frequency clocking for image processing applications

The need for high-performance image processing systems has led to the design and development of several application-specific parallel processing systems. An SIMD linear array processor with dynamic frequency clocking is proposed for real-time image processing applications. The architecture uses a novel concept called dynamic frequency clocking which allows the processor to vary the clock frequency dynamically based on the operation being performed. A VLSI chip based on the proposed architecture has been designed and verified using the Cadence design tools. The chip will operate at between 400 and 50 MHz based on the operation being performed. Several low-level image processing tasks have been mapped onto the architecture to evaluate the system performance and to demonstrate the effectiveness of the dynamic frequency clocking scheme.

A low-cost, 300-MHz, RISC CPU with attached media processor

This paper describes the 300-MHz StrongARM 1500 microprocessor, which is capable of more than two billion 16-b operations per second. Starting with the original StrongARM 110 design, an attached media processor (AMP) has been integrated along with a synchronous DRAM memory controller and separate I/O bus. In addition, several enhancements have been made to the CPU and cache subsystem, and the chip has been shrunk from a 0.35-to a 0.28-/spl mu/m technology. The chip includes 3.3 million transistors and measures 60 mm/sup 2/. It dissipates less than 3 W at 300 MHz at 2.0-V internal, 3.3-V I/O. The chip supports dynamic clock frequency switching for reduced operating power during low performance demands. There are 333 separately conditioned clocks on the chip, For battery-powered applications, V/sub dd/ can be reduced to achieve <0.5 W operation at 150 MHz. The chip is pseudostatic and can support clock stop and quiescent supply current testing. It implements the ARM V4 instruction set [1].