Soo-Kwan Eo

PowerV i P: Soc power estimation framework at transaction level

In this work, we propose a SoC power estimation framework built on our system-level simulation environment. Our framework provides designers with the system-level power profile in a cycle-accurate manner. We target the framework to run fast and accurately, which is enabled by adopting different modeling techniques depending on the power characteristics of various IP blocks. The framework can be applied to any target SoC design

Fast exploration of parameterized bus architecture for communication-centric SoC design

For successful SoC design, efficient and scalable communication architecture is crucial. Some bus interconnects now provide configurable structures to meet this requirement of an SoC design. Furthermore, bus IP vendors provide software tools that automatically generate RTL codes of a bus once its designer configures it. Configurability, however, imposes more challenges upon designers because complexity involved in optimization increases exponentially as the number of parameters grows. In this paper, we present a novel approach with which effort requirement can be dramatically reduced. An automated optimization tool we developed is used and it exploits a genetic algorithm for fast design exploration. This paper shows that the time for the optimizing task can be reduced by more than 90% when the tool is used and, more significantly the task can be done without an experts hand while ending up with a better solution.

A practical approach of memory access parallelization to exploit multiple off-chip DDR memories

3D stacked memory enables more off-chip DDR memories. Redesigning existing IPs to exploit the increased memory parallelism will be prohibitively costly. In our work, we propose a practical approach to exploit the increased bandwidth and reduced latency of multiple off-chip DDR memories while reusing existing IPs without modification. The proposed approach is based on two new concepts: transaction id renaming and distributed soft arbitration. We present two on-chip network components, request parallelizer and read data serializer, to realize the concepts. Experiments with synthetic test cases and an industrial strength DTV SoC design show that the proposed approach gives significant improvements in total execution cycle (21.6%) and average memory access latency (31.6%) in the DTV case with a small area overhead (30.1% in the on-chip network, and less than 1.4% in the entire chip).

Creation and utilization of a virtual platform for embedded software optimization:: an industrial case study

Virtual platform (ViP), or ESL (electronic system level) simulation model, is one of the most widely renowned system level design techniques. In this paper, we present a case study of creating and applying the ViP in the development of a new hard disk system called hybrid-HDD that is one of the main features in the Windows VISTA (R). First, we summarize how we developed the ViP including the levels of timing accuracy of models, automatic generation of models from RTL code, external subsystem models, etc. Then, we explain how we exploited the ViP in software optimization. Compared with the conventional flow of software development, e. g. based on the real board, the ViP gives a better profiling capability thereby allowing designers to find more chances of code optimization. Based on the simulation and analysis with the ViP, the software optimization could improve system performance by more than 50%. However, in our case study, we found that the current ViP technique needs further improvements to become a true ESL design technique.

Dynamic voltage scaling of supply and body bias exploiting software runtime distribution

This paper presents a method of dynamic voltage scaling (DVS) that tackles both switching and leakage power with combined Vdd/Vbs scaling and gives minimum average energy consumption exploiting the runtime distribution of software execution. We present a mathematical formulation of the DVS problem and an efficient numerical solution. Experimental results show that the presented method shows up to 44% further reduction in energy consumption compared with existing methods. Especially, when the leakage power consumption is significant, i.e. when temperature is high, the presented method is proven to be the most effective.

Fast and Accurate Transaction Level Modeling of an Extended AMBA2.0 Bus Architecture

A transaction level modeling (TLM) approach is used to meet the simulation speed as well as cycle accuracy for large scale SoC performance analysis. We implemented the transaction-level model of a proprietary bus called AHB+ which supports an extended AMBA2.0 protocol. The AHB+ transaction-level model is shown to be 353 times faster than the pin-accurate RTL model, while maintaining 97% accuracy on average. We also present the TLM development procedure of a bus architecture.

An open-loop flow control scheme based on the accurate global information of on-chip communication

3D stacked memory is being adopted as a promising solution to offer high bandwidth and low latency in memory access. Compared with the on-chip network design with conventional off chip memory, it gives a new problem of minimizing communication conflicts since multiple concurrent high bandwidth data transfers will flow through the on-chip network. In order to tackle this problem, we propose applying an open-loop flow control scheme based on the accurate global information (destination and status) of on-chip communication. The proposed open-loop flow control scheme exploits the information and selectively buffers and arbitrates data transfers to remove conflicts at destinations in a preventive manner. As an implementation of the presented scheme, we present on-chip buffers called Buf3Ds that share the global information with each other to perform the selective buffering and arbitration of data transfers. Experiments with synthetic test cases and an industrial strength DTV design show that the proposed method improves aggregate memory bandwidth significantly (average 19.0 %~25.8 % in the synthetic cases and up to 18.4 % in the DTV case) with a small area overhead (15.2 % in the DTV case) of on-chip network.

A systematic IP and bus subsystem modeling for platform-based system design

The topic on platform-based system modeling has received a great deal of attention today. One of the important tasks that significantly affect the effectiveness and efficiency of the system modeling is the modeling of IP components and communication between IPs. To be effective, it is generally accepted that the system modeling should be performed in two steps; In the first step, a fast but some inaccurate system modeling is considered to facilitate the simultaneous development of software and hardware. The second step then refines the models of the software and hardware blocks (i.e., IPs) to increase the simulation accuracy for the system performance analysis. Here, one critical factor required for a successful system modeling is a systematic modeling of the IP blocks and bus subsystem connecting the IPs. In this respect, this work addresses the problem of systematic modeling of the IPs and bus subsystem in different levels of refinements. In the experiments, we found that by applying our proposed IP and bus modeling methods to the MPEG-4 application, we are able to achieve 4times performance improvement and at the same time, reduce the software development time by 35%, compared to that by conventional modeling methods

An industrial perspective of power-aware reliable SoC design

Reliable SoC design is becoming one of important real design problems since the fast pace of semiconductor scaling and the introduction of new device structures and materials incur more reliability problems than can be solved in the given time frame (2 years/technology node). Reliable design mostly requires resource overhead (additional power consumption, silicon area, and execution time) to recover from errors. Minimizing the overhead in the reliable SoC design will give SoC industries a competitive edge. Especially, in the case of mobile SoC, mastering the overhead of power consumption is absolutely imperative. In this paper, we investigate reliable SoC design in terms of reducing the overhead of power consumption. First, we review the current practice of reliable SoC design and assess its impact on power consumption. Then, we present our perspective on new design methodology towards power-aware reliable SoC design.