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Description
Vision processing on traditional architectures is inefficient due to energy-expensive off-chip data movements. Many researchers advocate pushing processing close to the sensor to substantially reduce data movements. However, continuous near-sensor processing raises the sensor temperature, impairing the fidelity of imaging/vision tasks.

The work characterizes the thermal implications of using 3D stacked

Vision processing on traditional architectures is inefficient due to energy-expensive off-chip data movements. Many researchers advocate pushing processing close to the sensor to substantially reduce data movements. However, continuous near-sensor processing raises the sensor temperature, impairing the fidelity of imaging/vision tasks.

The work characterizes the thermal implications of using 3D stacked image sensors with near-sensor vision processing units. The characterization reveals that near-sensor processing reduces system power but degrades image quality. For reasonable image fidelity, the sensor temperature needs to stay below a threshold, situationally determined by application needs. Fortunately, the characterization also identifies opportunities -- unique to the needs of near-sensor processing -- to regulate temperature based on dynamic visual task requirements and rapidly increase capture quality on demand.

Based on the characterization, the work proposes and investigate two thermal management strategies -- stop-capture-go and seasonal migration -- for imaging-aware thermal management. The work present parameters that govern the policy decisions and explore the trade-offs between system power and policy overhead. The work's evaluation shows that the novel dynamic thermal management strategies can unlock the energy-efficiency potential of near-sensor processing with minimal performance impact, without compromising image fidelity.
ContributorsKodukula, Venkatesh (Author) / LiKamWa, Robert (Thesis advisor) / Chakrabarti, Chaitali (Committee member) / Brunhaver, John (Committee member) / Arizona State University (Publisher)
Created2019
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Description
With the end of Dennard scaling and Moore's law, architects have moved towards

heterogeneous designs consisting of specialized cores to achieve higher performance

and energy efficiency for a target application domain. Applications of linear algebra

are ubiquitous in the field of scientific computing, machine learning, statistics,

etc. with matrix computations being fundamental to these

With the end of Dennard scaling and Moore's law, architects have moved towards

heterogeneous designs consisting of specialized cores to achieve higher performance

and energy efficiency for a target application domain. Applications of linear algebra

are ubiquitous in the field of scientific computing, machine learning, statistics,

etc. with matrix computations being fundamental to these linear algebra based solutions.

Design of multiple dense (or sparse) matrix computation routines on the

same platform is quite challenging. Added to the complexity is the fact that dense

and sparse matrix computations have large differences in their storage and access

patterns and are difficult to optimize on the same architecture. This thesis addresses

this challenge and introduces a reconfigurable accelerator that supports both dense

and sparse matrix computations efficiently.

The reconfigurable architecture has been optimized to execute the following linear

algebra routines: GEMV (Dense General Matrix Vector Multiplication), GEMM

(Dense General Matrix Matrix Multiplication), TRSM (Triangular Matrix Solver),

LU Decomposition, Matrix Inverse, SpMV (Sparse Matrix Vector Multiplication),

SpMM (Sparse Matrix Matrix Multiplication). It is a multicore architecture where

each core consists of a 2D array of processing elements (PE).

The 2D array of PEs is of size 4x4 and is scheduled to perform 4x4 sized matrix

updates efficiently. A sequence of such updates is used to solve a larger problem inside

a core. A novel partitioned block compressed sparse data structure (PBCSC/PBCSR)

is used to perform sparse kernel updates. Scalable partitioning and mapping schemes

are presented that map input matrices of any given size to the multicore architecture.

Design trade-offs related to the PE array dimension, size of local memory inside a core

and the bandwidth between on-chip memories and the cores have been presented. An

optimal core configuration is developed from this analysis. Synthesis results using a 7nm PDK show that the proposed accelerator can achieve a performance of upto

32 GOPS using a single core.
ContributorsAnimesh, Saurabh (Author) / Chakrabarti, Chaitali (Thesis advisor) / Brunhaver, John (Committee member) / Ren, Fengbo (Committee member) / Arizona State University (Publisher)
Created2018
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Description
Digital systems are essential to the technological advancements in space exploration. Microprocessor and flash memory are the essential parts of such a digital system. Space exploration requires a special class of radiation hardened microprocessors and flash memories, which are not functionally disrupted in the presence of radiation. The reference design

Digital systems are essential to the technological advancements in space exploration. Microprocessor and flash memory are the essential parts of such a digital system. Space exploration requires a special class of radiation hardened microprocessors and flash memories, which are not functionally disrupted in the presence of radiation. The reference design ‘HERMES’ is a radiation-hardened microprocessor with performance comparable to commercially available designs. The reference design ‘eFlash’ is a prototype of soft-error hardened flash memory for configuring Xilinx FPGAs. These designs are manufactured using a foundry bulk CMOS 90-nm low standby power (LP) process. This thesis presents the post-silicon validation results of these designs.
ContributorsGogulamudi, Anudeep Reddy (Author) / Clark, Lawrence T (Thesis advisor) / Holbert, Keith E. (Committee member) / Brunhaver, John (Committee member) / Arizona State University (Publisher)
Created2016
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Description
The last decade has witnessed a paradigm shift in computing platforms, from laptops and servers to mobile devices like smartphones and tablets. These devices host an immense variety of applications many of which are computationally expensive and thus are power hungry. As most of these mobile platforms are powered by

The last decade has witnessed a paradigm shift in computing platforms, from laptops and servers to mobile devices like smartphones and tablets. These devices host an immense variety of applications many of which are computationally expensive and thus are power hungry. As most of these mobile platforms are powered by batteries, energy efficiency has become one of the most critical aspects of such devices. Thus, the energy cost of the fundamental arithmetic operations executed in these applications has to be reduced. As voltage scaling has effectively ended, the energy efficiency of integrated circuits has ceased to improve within successive generations of transistors. This resulted in widespread use of Application Specific Integrated Circuits (ASIC), which provide incredible energy efficiency. However, these are not flexible and have high non-recurring engineering (NRE) cost. Alternatively, Field Programmable Gate Arrays (FPGA) offer flexibility to implement any application, but at the cost of higher area and energy compared to ASIC.

In this work, a spatially programmable architecture customized for image processing applications is proposed. The intent is to bridge the efficiency gap between ASICs and FPGAs, by offering FPGA-like flexibility and ASIC-like energy efficiency. This architecture minimizes the energy overheads in FPGAs, which result from the use of fine-grained programming style and global interconnect. It is flexible compared to an ASIC and can accommodate multiple applications.

The main contribution of the thesis is the feasibility analysis of the data path of this architecture, customized for image processing applications. The data path is implemented at the register transfer level (RTL), and the synthesis results are obtained in 45nm technology cell library from a leading foundry. The results of image-processing applications demonstrate that this architecture is within a factor of 10x of the energy and area efficiency of ASIC implementations.
ContributorsSatapathy, Saktiswarup (Author) / Brunhaver, John (Thesis advisor) / Clark, Lawrence T (Committee member) / Ren, Fengbo (Committee member) / Arizona State University (Publisher)
Created2016