Reconfigurable/Adaptable Systems

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Reconfigurable/Adaptable Systems OS

• Michelle Grieco

Charles Huntington
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Reconfigurable/Adaptable Systems

• OS reconfigures its resource management policies
  based on application needs
• System components change and OS must adjust

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Reconfigurable OS

• Trends in Dynamically Reconfigurable Operating
  Systems include
• Plug and Play
• Hot Swappable Devices (PCMCIA and USB devices)
• Object Oriented Operating Systems

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Legacy Devices

• Prior to 1995 traditional computer cards had to
  be manually configured. This type of hardware is
  categorized as legacy devices.
• The hardware came with dip switches, and/or
  jumpers to configure their settings.
• The problem A user had to understand extensively
  how their computers resources were allocated to
  setup new hardware.
• Another problem A legacy devices default
  settings caused conflicts in resource allocation
  (ex sound cards, network adapters IRQ 5).

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Plug and Play
Devices now work out of the box.
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Plug and Play

• Microsoft, Intel, and a few other hardware
  manufacturers developed the Plug and Play (PnP)
  standard to combat the problems with Legacy
  Devices.
• A PnP OS stores the device drivers for many
  peripheral devices.
• PnP works with the BIOS to determine the
  necessary resources for new hardware.

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How PnP works...

• The BIOS first searches the PCI and ISA busses to
  determine if the current hardware matches the
  existing configuration.
• If the configuration has changed then the BIOS
  will assign resources to the legacy devices
  first.
• The PnP devices are update with the leftover
  resources.
• The ESCD (Extended System Configuration Data) is
  updated with the new configuration settings.

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PnP Problems

• After Windows 95 was out problems with PnP became
  apparent.
• Stubborn IRQ assignments
• PnP could not handle the complicated jobs.
• Plug and Pray?

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Hot Swapping

• Hot Swapping is the act of connecting/disconnectin
  g a device without stopping the host operations.
• Hot Swapping requires specially designed hardware
  and software.
• Hot Swapping requires that both the OS and the
  connecting peripheral support it.

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USB

• Universal Serial Bus is truly a PnP connector.
• USB is very fast, with a maximum bandwidth of 12
  Mbps
• USB is Hot-Swappable.

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Reconfigurable OS
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Dynamic Reconfiguration of OS using Objects

• Traditional systems use fixed management policies
• They can not expand (or contract) in order to run
  under new hardware environments.
• They can not implement a new feature just because
  the hardware made it available.
• Dynamic reconfiguration welcomes new
  implementations of hardware where traditional OS
  ignore it.

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Reconfiguration of OS using Objects

• One example of an OO Reconfigurable OS is
  Choices.
• Choices can run on many different hardware
  platforms.
• Choices uses three main abstract classes
  MemoryObject, Process and Domain.
• These classes define the rest of the OS.

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Choices steps to a new OS

• The automatic development of a subframework, like
  a file system, is handled in the following
  manner.
• The abstract properties of the subsystem are
  collected (file permissions, containing data
  structure and compression techniques).
• A subframework is developed that is consistent
  with the absract properties and the lower level
  requirements.
• Finally a subsystem is created with concrete
  classes that exemplifies the subframework.

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Choices three abstract classes
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Choices constraints
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Choices subframework
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Reconfigurable System Components
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Wearable Reconfigurable Computers
Quantum3D
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Requirements

• Occasionally execute bursts of computation-intensi
  ve tasks that carry real-time constraints
  (reading sensor position, cryptography and
  communication) high energy efficiency and
  performance
• Fixed base performance for running tasks that
  have neither high computation demands nor
  stringent timing constraints.
• Low power consumption force components into
  power-down modes
• Highly flexible components of systems are
  dynamically added (put on or removed from the
  body system)
• Adapt to emerging/changing communication
  standards/protocols

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High Performance Reconfigurable Computer Systems
- Example

• Wearable Configurable Systems
• Embedded into mobile environment that interacts
  with to events occurring in the area
• Composed of a set of distributed nodes and a
  communication network surrounded by a general
  purpose main module
• Performance intensive parts are implemented in
  FPGAs (reconfigurable), but the system also
  contains low power CPUs
• Wireless is the predominant technology of
  communication with outside networks

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FPGAs

• Field Programmable Gate Arrays
• Programmable logic blocks which are
  interconnected by programmable routing channels
• SRAM based cells control the functionality of the
  logic blocks and routing
• Reprogrammed in-circuit arbitrarily by
  downloading configuration data to the device

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Components of Reconfigurable Systems
Reconfigurable Hardware
CPU
Sensors Interface
Memory
Wireless Link

• Integration of CPU and FPGAs allows for low
  latency and low power communication
• Energy savings of moving kernels to FPGA instead
  of CPU
• Computation intensive functions are loaded into
  reconfigurable hardware as needed. It can also
  run communication function protocol functions to
  relieve the CPU
• The reconfigurable hardware is known as ASIC
  on-demand.
• Application-Specific Integrated Circuit - a chip
  designed for a particular application (as opposed
  to the integrated circuits that control functions
  such as RAM in a PC).
• ASICs are built by connecting existing circuit
  building blocks in new ways. Since the building
  blocks already exist in a library, it is much
  easier to produce a new ASIC than to design a new
  chip from scratch.

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Reconfigurable System Software Architecture
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Pros Cons ofHigh Performance Reconfigurable
Computing

• Pros
• Exponential improvement of capabilities and
  performance using FPGAs
• Flexibility
• Modest Cost

• Cons
• Programming HP computers is time consuming
• Must be expert in parallel computing
  architecture, programming tools and target
  application

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Reconfigurable Systems

• Demand paged hardware similar to virtual memory
  used for software
• Each computation task can be supported by the
  notion of virtual hardware.
• Different hw tasks could share portions of the
  FPGA physically or temporally and operate like a
  hardware cache.
• By using the reconfigurable components as virtual
  hardware, fewer resources are needed for an
  application since the RC units can be dynamically
  reconfigured and reused to implement multiple
  functions.

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References

• Supporting Dynamic Reconfiguration of Operating
  System using Object and Meta Objects. Yoo,
  Kwanghun and Choo, Yookun. Department of Computer
  Engineering. University of Seoul. IEEE. 1995.
  p727-733.
• When Virtual is Better than Real. Chen, Peter M.
  and Noble, Brian D. Department of Electrical
  Engineering and Computer Science. University of
  Michigan. IEEE. 2001. p133 138.
• What next? A Hardware Operating System? Groza,
  V., Abielmona, R. School of Information
  Technology Engineering, University of Ottawa,
  Canada. IEEE. 2004. p1496 1501.
• High Performance Reconfigurable Computing
  Systems. Smith, M., Drager, S., Pochet, L.,
  Peterson, G. University of Tennessee Electrical
  and Computer Engineering. Air Force Research
  Laboratory. IEEE. 2001. p 462 465.
• Reconfigurable Hardware in Wearable Computing
  Nodes. Plessl, C., Enzler R., Walker, H.,
  Beutel, J., Platzner, M., Thiele, L. Swiss
  Federal Institute of Technology. IEEE.
  Proceedings of the 6th International Symposium on
  Wearable Computers. 2002.

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References

• How does USB Work?. Ken Jacobs. August 5, 2004.
  Http//www.pcmech.com/show/internal/681/.
• Plug and Play, A how to manual.
  http//www.tldp.org/HOWTO/Plug-and-Play-HOWTO.html
  toc4.
• On Adaptable Aspect-Oriented Operating Systems.
  Daniel Lohmann, Wasif Gilani and Olaf Spinczyk.
  Friedrich-Alexander-Unversity Eriangen-Nuremberg,
  Germany.
• Choices, Frameworks and Refinement. Roy H.
  Campbell, Nayeem Islam, Ralph Johnson, Panos
  Kougiouris and Peter Madany. Department of
  Computer Science. University of Illinois at
  Urbana-Champaign.
• Java Tip 30 Polymorphism and Java, What to do
  when switch statements start reappearing in your
  code. Philip Bishop. Http//www.javaworld.com/java
  tips/jw-javatip30_p.html.