System Architecture for Extreme Devices

1
System Architecture for Extreme Devices

• David Culler
• http//www.cs.berkeley.edu/culler
• U.C. Berkeley
• DARPA Meeting
• 9/21/1999

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Recap Convergence at the Extremes

• Arbitrarily Powerful Services on Small Devices
• massive computing and storage in the
  infrastructure
• active adaptation of form and content along the
  way
• Extremes more alike than either is to the middle
• More specialized in function
• Communication centric design
• wide range of networking options
• Federated System of Many Many Systems
• Hands-off operation, mgmt, development
• Scalability, High Reliability, Availability
• Power and space limited
• gt simplicity
• Each extends the other

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State-of-the-Art Very Large Systems

• Scalable Clusters Established
• high-speed user-level networking single system
  image
• naming, authentication, resources, remote exec.,
  storage, policy
• Meta-system glue over full OS and Institutional
  structure
• Glunix (UCB), Globus(ANL), Legion (UVA), IPG
  (NASA), Harness, NetSolve, Snipe (UTK), ...
• uniform, multiprotocol communication access
  mechanism
• personal virtual machine spanning potentially
  diverse resources
• constructed and managed by hand
• Key challenges
• Automatic Composition, Management, and
  Availability
• Scalability to global scale
• Ease of development for global-scale services

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State-of-the-Art in the small...

• Unix-like support in a small form factor real
  time seasoning
• microkernels dominate
• academic Exokernel, OSKit, ucLinux, ELKS,
• Commercial PSION, GeoWorks, WinCE, Inferno, QNX,
  VxWorks, javaos, chorusOS,
• PalmOS, BeOS,
• Components and mobile objects jini, corba, dcom,
  ...
• gt tracks the 80386
• when it becomes 1990 PC Unix will run on it
• ability to remove components (modularity) fault
  boundaries more important than performance
• legacy applications less dominant

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Design Issues for Small Device OS

• Current Managing address spaces,Thread
  scheduling, IP stack, Windowing System, Device
  drivers, File system, Applications Programming
  Interface, Power management
• Challenge How can operating systems for tiny
  devices be made radically simpler, manageable,
  and automatically composable?

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Emerging Devices

• RF COTS Mote
• Atmel Microprocessor
• RF Monolithics transceiver
• 916MHz, 20m, 4800 bps
• 1 week fully active, 2 yr _at_1

• Laser mote
• 650nm laser pointer
• 2 day life full duty

• CCR mote
• 4 corner cubes
• 40 hemisphere

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Micro Mote - First Attempt
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Structured Communication-Centric System
Architecture

• Scalable Info Utility Providers
• highly available
• persistent state (safe)
• databases, agents
• service programming environment

• Active Proxies
• connected to the infrastructure
• soft-state, bootstrap protocol
• transcoding,

• Ubiquitous Devices
• billions
• sensors / actuators
• PDAs / smartphones / PCs
• heterogeneous

• Service Paths
• aggregate flows (rivers)
• transcoding operators

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New Kinds of Nodes become Key

• Infrastructure Nodes
• powerful network lots of proc. and storage
• interact through the network
• Transducer Nodes
• network sensors or actuators
• limited processing and state
• Interaction Nodes
• network user interface
• widely varying capability and size
• Communication is the common element

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The Large Service-Centric Platform Arch
Infrastructure Services

• Information Utility is not just storage. It must
  enable
• Distributed Innovation of Scalable, Avail.
  Services
• service registry, aggregate execution env.,
  transparency
• persistent dist. data structures
• massive fluid storage (ocean)
• adaptive high-bandwidth flows (rivers)
• Build the infrastructure itself through
  composition of services

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Automated Composition and Mgmt

• Individual services are strongly-typed active
  components that can be located through
  intentional service discovery
• Application formed as path (or graph) of services
• not ad hoc connectivity, nor general planning
• reachability and adaptation
• Resources allocated and managed in decentralized
  manner under economic model
• translation of value -gt resource
• platform components enforce allocation
• rich body of mechanisms (contracts, auctions,
  pricing)
• natural elevation from resources to higher level
  services
• gt Simple composition building from complex nodes

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The Small radically simple OS for management and
composition

• Communication is fundamental
• treated as part of the hardware. No comm. is
  like no power
• hands off a direct user interface is the
  exception not the norm
• typical device has a network on one side
  sensor/actuators on the other
• buttons and display a special case
• all deployment, development, configuration, mgmt,
  programming, is through the communication
  interface
• schedule data movement, not arbitrary threads of
  computation

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OS as little more than FSM

• Primary focus is scheduling discrete chunks of
  data movement
• not general thread scheduling and unlimited
  memory management
• there may be a bounded amount of work to xform or
  check data
• Commands are an event stream merged with
  sensor/actuator events
• General thread must be compiled to sequence of
  bounded atomic transactions
• spaghetti part of an application is configuring
  the flows
• steady-state is straight-forward event processing
  signaling unusual events
• constant self-checking and telemetry
• rely on the infrastructure for hard stuff
• correct-by-construction techniques for
  cooperating FSMs

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Precursors to the next generation

• Operating systems that are not called operating
  systems
• eg modern disk controller
• event scheduler handling stream of commands from
  network link, controlling complex array of
  sensors and actuators, performing sophisticated
  calculations to determine what and when
  (scheduling and caching) as well as transforming
  data on the fly
• automatic connection, enumeration, configuration
• but several simplifying assumptions must be
  removed

Complex array of Sensors and actuators
Network link - EIDE, SCSI - FCAL, SSA - USB,
1394 - ???
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UCB Testbed
Cell Phones

• 1x300 proc 10x20 proc SAN clusters across
  depts.
• integrated through multiple gigabit ethernet
• extended out throug 100s desktops, RF laptop,
  IRDA PDA, Cell Phones, Pagers, and numerous motes

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Plan

• Prototype Phase
• Large 2nd generation NOW arch. meta-OS efforts
  Ninja Service Platform
• Small PalmOS wince uc-Linux
• simulation environment
• Develop
• Automated service composition architecture
• FSM-OS and negotiation/mgmt architecture
• Deploy widespread services, devices and feeds
• Evaluate against high-speed decision making
  applications