Multiprocessors for DSP

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Multiprocessors for DSP

• SYSC5603 Digital Signal Processing
  Microprocessors, Software and Applications
  

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Outline

• Why Multiprocessor Systems?
• Chip Multiprocessor (CMP) Architectures
• CMP Advantages Disadvantages
• Current CMP Solutions
• Tools for Designing and Simulation CMPs
• Summary

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Why Multiprocessor Systems?

• Single-core microprocessor performance increases
  are beginning to slow 1 due to
• Increasing power consumption (gt100 W)
• Increasing heat dissipation
• Diminishing performance gains from ILP TLP 2
• As a result manufactures are turning to a
  multi-core microprocessor approach
• Multiple smaller energy efficient processing
  cores are integrated onto a single chip
• Improves overall performance by performing more
  work concurrently

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CMP Architectures

• Two general types of multi-core or chip
  multiprocessor (CMP) architectures
• Homogeneous CMPs all processing elements (PEs)
  are the same
• Heterogeneous CMPs comprised of different PEs
• Homogenous dual-core processors for PCs are now
  available from all major manufactures
• Heterogeneous CMPs are available in the form of
  multiprocessor systems-on-chips (MPSoCs)

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Homogenous CMP - Quad-SHARC DSP
Quad-SHARC Functional Diagram
Core ADSP-21060 SHARC Functional Diagram
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3
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Heterogeneous CMP Cell BE
Cell Broadband Engine Block Diagram
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CMP Advantages

• CMPs have several advantages over single
  processor solutions
• Energy and silicon area efficiency
• By Incorporating smaller less complex cores onto
  a single chip
• Dynamically switching between cores and powering
  down unused cores 5
• Increased throughput performance by exploiting
  parallelism
• Multiple computing resources can take better
  advantage of instruction, thread, and process
  level parallelism

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CMP Disadvantages

• Poorer performance in single task situations
• Need to have software that can be decomposed into
  multiple threads in order to take full advantage
  of CMP resources
• Programming CMPs is inherently more difficult due
  to
• Software needing to be designed with multiple
  threads
• Parallel programming and its associated issues
  such as shared memory access and message passing
• Large number of possibly different types of PEs

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Current CMP Solutions

• Many different types of CMP solutions exist today
  and choosing one depends on the intended
  application
• In the desktop computing industry all major
  manufactures now offer multi-core solutions
• Manufactures of PDSPs also offer multi-core
  versions of their products
• FPGA manufactures offer programmable devices with
  immersed microprocessor cores

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Design and Simulation Tools

• Of the multi-core solutions that exist none offer
  support for a multi-core design from scratch
• Instead customers decide on a multi-core platform
  from a specific vendor and generally use the
  tools available from that vendor to program,
  test, and verify their multi-core solution
• One solution for the design and simulation of
  multi-processor systems from the ground up is
  offered by Cmpware Inc.
• They offer a configurable multi-processor
  development kit (CMP-DK) which allows for the
  design, programming, and testing of
  multi-processor systems

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Design and Simulation Tools The CMP-DK

• Their development environment lets processors and
  their interconnection network be quickly and
  simply defined 6
• Existing processor cores along with their
  associated tools, libraries, and software can be
  used 6
• Also, users are able to specify their own custom
  processor architectures and interconnect networks
  or modify an existing architecture as needed.

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Summary

• The CMP architecture is now the architecture of
  choice for semiconductor manufactures
• CMPs are more area and energy efficient than
  single processor solutions
• CMPs achieve greater throughput than single
  processor solutions as more work can be done
  concurrently
• Custom multi-processor systems can now be
  designed and simulated from the ground up using
  software solutions from several companies

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References

• 1 D. Geer, Chip makers turn to multicore
  processors, IEEE Computer, vol. 38, no. 5, pp.
  11-13, 2005.
• 2 L. Hammond, B. Hubbert, M. Siu, M. Prabhu, M.
  Chen and K. Olukotun, The Stanford Hydra CMP,
  IEEE Micro, vol. 20, no. 2, pp. 71-84, Mar./Apr.
  2000.
• 3 AD14060 Data Sheets. (2004). Analog Devices.
  Norwood, MA. Online. Available
  http//www.analog.com/UploadedFiles/Data_Sheets/
  4003696AD14060_L_b.pdf
• 4 Cell Broadband Engine Architecture and its
  first implementation. Online. Available
  http//www- 128.ibm.com/developerworks/power/libr
  ary/pa- cellperf/23ref1

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References

• 5 R. Kumar, D. M. Tullsen, N.P. Jouppi, and P.
  Ranganathan, Heterogeneous Chip
  Multiprocessors, IEEE Computer, vol. 38, no.
  11, pp. 32-38, 2005.
• 6 S. A. Guccione. (2005, April). Programming
  Configurable Multiprocessors. Presented at the
  12th Reconfigurable Architectures Workshop.
  Online. Available http//www.cmpware.com/Pape
  rs/RAW2005/Cmpwar e_RAW_2005.pdf