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The Microprocessor is no more General Purpose. Design Gap.

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Presentation on theme: "The Microprocessor is no more General Purpose. Design Gap."— Presentation transcript:

1 The Microprocessor is no more General Purpose

2 Design Gap

3 Problems with Fine Grained Approach FPGAs Area in-efficient – Percentage of chip area for wiring far too high Too slow – Unavoidable critical paths too long Routing and Placement is very complex

4 Problems with Fine Grained FPGAs

5 Coarse Grained Reconfigurable computing Uses reconfigurable arrays with path-widths greater than 1 bit More area-efficient Massive reduction in configuration memory and configuration time Drastic reduction in complexity of Placement & Routing

6 Coarse Grained Architectures Classification Mesh-based Linear Arrays based Cross-bar based

7 Mesh Based Architectures Arranges PEs in a 2-D array Encourages nearest neighbor links between adjacent PEs Eg. KressArray, Matrix, RAW, CHESS

8 Matrix – Mesh based Architecture

9 Matrix – Mesh Based Architecture

10 Architectures based on Linear Arrays Aimed at mapping pipelines on linear arrays If pipeline has forks longer lines spanning whole or part of the array are used Eg. RaPiD, PipeRench

11 PipeRench – Linear Array based architecture

12 PipeRench – Linear Array Based Architecture

13 Cross-bar based Architectures Communication Network is easy to route Uses restricted cross-bars with hierarchical interconnect to save area Eg. PADDI-1, PADDI-2, Pleiades

14 PADDI-2 – Cross-bar based architecture

15 PADDI-2 Cross-bar based Architecture

16 Coarse Grained Architectures

17 EGRA Architectural template to enable design space exploration Execute expressions as opposed to operations Supports heterogeneous cells and various memory interfaces


19 Evolution of fine grained and coarse grained architectures

20 EGRA – at Cell Level

21 Architectural Exploration

22 Architectural exploration


24 EGRA – at array level Organized as a mesh of cells of three types – RACs – Memories – Multipliers Cells are connected using both nearest neighbor and horizontal-vertical buses Each cell has a I/O interface, context memory and core

25 Control Unit

26 EGRA Operation DMA mode – Used to transfer data in bursts to EGRA – To program cells and to read/write from scratchpad memories Execution mode – Control unit orchestrates data flow between cells

27 EGRA – at array level

28 Experimental Results



31 EGRA Memory Interface Data register at the output of computational cells Memory cells can be scattered around in the array A scratchpad memory outside reconfigurable mesh

32 Architectural exploration - Area

33 Architectural exploration - Delay


35 The reconfigurable Cell

36 Operating modes of RC

37 Interconnection Topology Hierarchical – Level 1 used within 4x4 quadrant to provide nearest neighbor connectivity – Interleaved Horizontal and Vertical connectivity of length two – Each RC can receive data from at most two other RCs and send data to at-most four other RCs – Data and control across quadrants is guaranteed over Level 2 interconnection

38 Interconnection Topology

39 Computational Strategies Temporal computational load balancing Spatial computational load balancing

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