This paper introduces a methodology to develop energy models for the design space exploration of embedded many-core systems. The design process of such systems can benefit from sophisticated models. Software and hardware can be specifically optimized based on comprehensive knowledge about application scenario and hardware behavior. The contribution of our work is an automated framework to estimate the energy consumption at an arbitrary abstraction level without the need to provide further information about the system. We validated our framework with the configurable many-core system CoreVA-MPSoC. Compared to a simulation of the CoreVA-MPSoC on gate level in a 28nm FD-SOI standard cell technology, our framework shows an average estimation error of about 4 .
Besides the target platform or components the aforementioned work further differs in their methodology. The McPat framework @cite_6 estimates energy based on a model specification while other work gathers data from various sources to fit models like Ortiz et al. did by measuring the MPSoC @cite_7 . Multiple options to create and gather data for the second option may be found in research. Microbenchmarks which are often handwritten are used for the behavior creation in contrast to real applications or benchmark suits. Furthermore data can be gathered by simulating those systems or by measuring final ASICs under real world conditions. The simulation method provides fine granular power analysis, e.g. it is possible to gather power data for all components of a CPU using gate level analysis at the cost of an often compute intensive but scalable simulation Finally, the simulation method is able to provide data before tape out and it is able to simulate various environment conditions. While the measurement method provides better accuracy because it incorporates all physical effects and uses real word conditions.
@cite_7 @cite_6
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This paper introduces McPAT, an integrated power, area, and timing modeling framework that supports comprehensive design space exploration for multicore and manycore processor configurations ranging from 90nm to 22nm and beyond. At the microarchitectural level, McPAT includes models for the fundamental components of a chip multiprocessor, including in-order and out-of-order processor cores, networks-on-chip, shared caches, integrated memory controllers, and multiple-domain clocking. At the circuit and technology levels, McPAT supports critical-path timing modeling, area modeling, and dynamic, short-circuit, and leakage power modeling for each of the device types forecast in the ITRS roadmap including bulk CMOS, SOI, and doublegate transistors. McPAT has a flexible XML interface to facilitate its use with many performance simulators. Combined with a performance simulator, McPAT enables architects to consistently quantify the cost of new ideas and assess tradeoffs of different architectures using new metrics like energy-delay-area2 product (EDA2P) and energy-delay-area product (EDAP). This paper explores the interconnect options of future manycore processors by varying the degree of clustering over generations of process technologies. Clustering will bring interesting tradeoffs between area and performance because the interconnects needed to group cores into clusters incur area overhead, but many applications can make good use of them due to synergies of cache sharing. Combining power, area, and timing results of McPAT with performance simulation of PARSEC benchmarks at the 22nm technology node for both common in-order and out-of-order manycore designs shows that when die cost is not taken into account clustering 8 cores together gives the best energy-delay product, whereas when cost is taken into account configuring clusters with 4 cores gives the best EDA2P and EDAP. The vast number of transistors available through modern fabrication technology gives architects an unprecedented amount of freedom in chip-multiprocessor (CMP) designs. However, such freedom translates into a design space that is impossible to fully, or even partially to any significant fraction, explore through detailed simulation. In this paper we propose to address this problem using predictive modeling, a well-known machine learning technique. More specifically we build models that, given only a minute fraction of the design space, are able to accurately predict the behavior of the remaining designs orders of magnitude faster than simulating them. In contrast to previous work, our models can predict performance metrics not only for unseen CMP configurations for a given application, but also for unseen configurations of a new application that was not in the set of applications used to build the model, given only a very small number of results for this new application. We perform extensive experiments to show the efficacy of the technique for exploring the design space of CMP's running parallel applications. The technique is used to predict both energy-delay and execution time. Choosing both explicitly parallel applications and applications that are parallelized using the thread-level speculation (TLS) approach, we evaluate performance on a CMP design space with about 95 million points using 18 benchmarks with up to 1000 training points each. For predicting the energy-delay metric, prediction errors for unseen configurations of the same application range from 2.4 to 4.6 and for configurations of new applications from 3.1 to 4.9 . Executing multiple applications on a single MPSoC brings the major challenge of satisfying multiple quality requirements regarding real-time, energy, and so on. Hybrid application mapping denotes the combination of design-time analysis with run-time application mapping. In this article, we present such a methodology, which comprises a design space exploration coupled with a formal performance analysis. This results in several resource reservation configurations, optimized for multiple objectives, with verified real-time guarantees for each individual application. The Pareto-optimal configurations are handed over to run-time management, which searches for a suitable mapping according to this information. To provide any real-time guarantees, the performance analysis needs to be composable and the influence of the applications on each other has to be bounded. We achieve this either by spatial or a novel temporal isolation for tasks and by exploiting composable networks-on-chip (NoCs). With the proposed temporal isolation, tasks of different applications can be mapped to the same resource, while, with spatial isolation, one computing resource can be exclusively used by only one application. The experiments reveal that the success rate in finding feasible application mappings can be increased by the proposed temporal isolation by up to 30 and energy consumption can be reduced compared to spatial isolation. Computer architects must determine how tomost effectively use finite computational resources whenrunning simulations to evaluate new architectural ideas.To facilitate efficient simulations with a range of benchmarkprograms, rn have developed the MinneSPEC inputset for the SPEC CPU 2000 benchmark suite. Thisnew workload allows computer architects to obtain simulationresults in a reasonable time using existing sirnulators.While the MinneSPEC workload is derived from thestandard SPEC CPU 2000 warklcad, it is a valid benchmarksuite in and of itself for simulation-based research.MinneSPEC also may be used to run Iarge numbers ofsimulations to find "sweet spots" in the evaluation parameterspace. This small number of promising designpoints subsequently may be investigated in more detailwith the full SPEC reference workload. In the processof developing the MinneSPEC datasets, we quantify itsdifferences in terms of function-level execution patterns,instruction mixes, and memory behaviors compared tothe SPEC programs when executed with the reference inputs.We find that for some programs, the MinneSPECprofiles match the SPEC reference dataset program behaviorvery closely. For other programs, however, theMinneSPEC inputs produce significantly different programbehavior. The MinneSPEC workload has been recognizedby SPEC and is distributed with Version 1.2 andhigher of the SPEC CPU 2000 benchmark suite.