Dynamic Resource Management in a Static Network Operating System Kevin Klues et. al. Presented By - Jay Abstract Novel resource management approaches. Static allocation of resources. Compile Time Virtualization of resources. Dynamic management. Keywords Resource Management
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Dynamic Resource Management in a Static Network Operating System
Kevin Klues et. al.
Presented By - Jay
Novel resource management approaches.
Static allocation of resources.
Compile Time Virtualization of resources.
Paper presents a novel architecture for resource management.
Dynamically Management between statically allocated resources and fixed no. of clients.
Different from traditional model of dynamic clients and dynamic memory allocation.
Mantis: Lightweight threads
SOS : Dynamic allocation, dynamic callbacks
Contiki : pure event driven in a thread like abstraction
Monitored pressure and humidity of 2 redwood trees.
Used Mica motes and TinyOS 1.0
Period of 6 weeks and collect one reading from 4 sensors every 5 minutes. Write to flash and send to PC over multi hop.
100 nodes used, only 33 worked, 67 died.
Some of the ad-hoc approaches used formed the basis of the research work of the paper.
Good system abstractions have 3 basic properties
Flexible, small no of abstractions
Simplify application programming
Static memory management vs. Dynamic memory management.
Weak type checking
Simple and efficient
More flexible, may lead to access errors
TinyOS : static allocation of memory vs. Others who follow dynamic. Mantis has 6 bytes overhead for every allocated block, Contiki uses the best-fit-freelist allocator, SOS is highly inefficient.
chip and peripheral devices power states.
on motes, most of the peripheral devices have only 2 power states - on / off.
micro controller has two power states - active and sleep
In TinyOS, telosb platform, sleep mode power consumption can be lowered to 2microA. Contiki can go low up to 75 micro A, SOS sits in busy loop (bad), Mantis uses idle state when all threads are blocked.
Managing access and powering off.
Sharing can be done using Turn based sharing or using Virtualized.
TinyOS uses virtualized timers.
SOS has no mechanism for sharing resources.
Mantis uses a mutex.
Allocate Statically, Manage Dynamically
Memory objects are of know size in static allocation.
Overrun and underrun errors are rare.
Use Buffer swapping.
On TinyOS , for peripherals, simple interface with stop and start commands
microcontroller power management is more complicated.
Achieved in 3 ways:
Compute mcuPowerState based on what Peripherals are on
Application need to set dirtyMcuState if they affect MCU
Hooks for application to specify a specific state.
T2: Virtualized or Shared
Exception of Timer, all Virtualized Services are built on top of Shared with access controlled by Arbiters.
Arbiters provide following interfaces:
Arbiter Types: First come first served, Round robin
Designed to make writing applications simpler while maintaining performance and achieving better energy efficiency.
Memory and PD, static allocation and compile time virtualization is used. At runtime, ownership is passed between clients removing the burden from application programmer.
Energy efficiency is achieved by automatically controlling the the power state of both microcontroller and all its PDs.