Towards Resource Aware Applications and Systems

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Towards Resource Aware Applications and Systems

• Michael B. Jones
• Microsoft Research

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Goal Coexisting Independent Real-time
Applications

• Independently developed
• Predictable concurrent execution of
• real-time and non-real-time apps
• Meeting all apps timing needs
• Informing apps when not possible

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Overview

• Need for Resource Management
• Motivating Examples
• Resource Awareness
• Call to Action

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Case for Explicit Resource Allocation and
Accounting

• Time-Sensitive applications need
• different resources
• at different rates
• in different amounts
• Even infinite resources insufficient if not given
  to apps in timely fashion

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Assumption Multiple Tasks

• Assumption
• Multiple concurrent tasks
• At least one time sensitive
• Many such tasks to choose from
• Media input, output
• Speech, vision-based UIs
• Software modems, sound cards, ...
• Industrial device control
• etc.

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One Real-Time Task Enough

• Time aware resource management needed even if
  just one real-time task
• Competing normal tasks can still cause real-time
  task to fail
• Round-robin with to large a period
• Fair share with too small a proportion

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Motivation User Interfaces

• User interfaces can use all the resources, all
  the time!
• Speech, vision understanding, implicit queries,
  etc. can use as much as they get
• Must manage background activities resource usage
  so real work gets done
• Low-latency responses required
• Camera-based head motion parallax driving 3D
  virtual environment needslt 200ms response
  50-100ms ideal
• Simple timesharing, priority schemes wont get
  the right tasks done at the right times

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Motivation Reducing Costs

• PC industry wants lower prices points
• Buying choice different below 400
• Soft Migration one means
• Remove extra CPUs, such as modem DSP
• 15 parts cost gt 45 retail cost
• Soft modems work well on 200MHz MMX
• Sample processing rates
• 12ms in normal operation
• 1.5ms during training
• Infeasible without appropriate scheduling

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Motivation Reliability

• Denial of Service attacks steal resources
• Resource management can guarantee resources to
  good clients
• Example Resource Container results protecting
  web servers from SIN attacks (Banga, Druschel,
  Mogul OSDI 99)

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Motivation Consumer Real-Time Applications

• Enable consumers to purchase or download
  applications
• some of which have real-time needs
• just like current shrink-wrapped Internet
  applications today
• with expectation independently developed apps
  will successfully coexist.

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Resource Awareness

• Only apps know their timing requirements
• must have a vocabulary for expressing them
• Only system can enforce resource guarantees
• must do resource accounting
• to fulfill negotiated resource guarantees
• Both must be Resource Aware

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Determining Application Resource Needs

• Adaptive approach
• 1. Observe own resource usage
• 2. Compute expected needs from past observations
• 3. Reserve appropriate resource amounts
• Resource self-aware applications key
• Only apps have knowledge to make appropriate
  resource tradeoffs
• Uncertainty in amounts inherent
• Caches, busses, CPU speeds, contention

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Missing Information Paths

• In current general-purpose systems
• Apps cant tell system
• when code needs to be executed
• amounts of resources they need
• System cant tell apps
• whether deadlines will be met
• amounts of resources available to them
• Both flying blind

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Call To Action

• Future systems must provide
• Explicit resource management interfaces
• Predictable low-latency scheduling
• Enabling technology for
• User interface advances
• Reduced cost computing
• More reliable computing
• Consumer real-time applications

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Towards Resource Aware Applications and Systems

• Discussion