System Architecture for Extreme Devices David Culler U.C. Berkeley DARPA Meeting 9/21/1999

9/21/99Endeavour Sys. Arch2 Away from the ‘average’ Device Scalable, Available Internet Services Info. appliances Client Server Clusters Massive Cluster Gigabit Ethernet

9/21/99Endeavour Sys. Arch3 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 –High Reliability, Availability –Scalability –Power and space limited –simplicity Each extends the other

9/21/99Endeavour Sys. Arch4 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),...GlunixGlobusLegionIPGHarness, NetSolve, Snipe –uniform, multiprotocol communication 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

9/21/99Endeavour Sys. Arch5 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, ExokernelOSKitucLinuxELKS »Commercial: PSION, GeoWorks, WinCE, Inferno, QNX, VxWorks, javaos, chorusOS,PSIONGeoWorksWinCEInfernoQNX VxWorksjavaoschorusOS –+ PalmOS, BeOS,+ PalmOSBeOS –Components and mobile objects: jini, corba, dcom,... => tracks the –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

9/21/99Endeavour Sys. Arch6 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?

9/21/99Endeavour Sys. Arch7 Emerging Devices RF COTS Mote –Atmel Microprocessor –RF Monolithics transceiver »916MHz, ~20m, 4800 bps –1 week fully active, 2 N S EW 2 Axis Mag. Sensor 2 Axis Accelerometer Light Intensity Sensor Humidity Sensor Pressure Sensor Temperature Sensor Laser mote 650nm laser pointer 2 day life full duty CCR mote 4 corner cubes 40% hemisphere

9/21/99Endeavour Sys. Arch8 Micro Mote - First Attempt

9/21/99Endeavour Sys. Arch9 Structured Communication-Centric Architecture Approach Active Proxies –connected to the infrastructure –soft-state, bootstrap protocol –transcoding, Ubiquitous Devices –billions –sensors / actuators –PDAs / smartphones / PCs –heterogeneous Service Path Base Scalable Infrastructure –highly available –persistent state (safe) –databases, agents –service programming environment Service Paths –aggregate flows (rivers) –transcoding operators

9/21/99Endeavour Sys. Arch10 Three Basic Kinds of Nodes Infrastructure Nodes –powerful network + lots of proc. and storage –interact through the network Transducer Nodes –network + sensors or actuators –limited proc and state Interaction Nodes –network + user interface –widely varying capability and size Communication is the common element

9/21/99Endeavour Sys. Arch11 The Large: Service-Centric Platform Arch Servers Clients Servers Infrastructure Services Open 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

9/21/99Endeavour Sys. Arch12 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 -> resource –platform components enforce allocation –rich body of mechanisms (contracts, auctions, pricing) –natural elevation from resources to higher level services => Simple composition building from complex nodes

9/21/99Endeavour Sys. Arch13 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

9/21/99Endeavour Sys. Arch14 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

9/21/99Endeavour Sys. Arch15 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, ???

9/21/99Endeavour Sys. Arch16 UCB Testbed 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 Cell Phones PDAs Future Devices Wireless Desktop PCs Servers Clusters Massive Cluster Gigabit Ethernet

9/21/99Endeavour Sys. Arch17 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