CS533 Concepts of Operating Systems Class 2 Thread vs Event-Based - - PowerPoint PPT Presentation

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CS533 Concepts of Operating Systems Class 2 Thread vs Event-Based - - PowerPoint PPT Presentation

Sep 05, 2023 355 likes •439 views

CS533 Concepts of Operating Systems Class 2 Thread vs Event-Based Programming Questions Why are threads lightweight? Why block instead of spin waiting for a mutex? If a mutex is a resource scheduling mechanism o What is the

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CS533 Concepts of Operating Systems Class 2 Thread vs Event-Based Programming

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CS533 - Concepts of Operating Systems

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CS533 - Concepts of Operating Systems

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Questions

 Why are threads “lightweight”?  Why block instead of spin waiting for a mutex?  If a mutex is a resource scheduling mechanism

  • What is the resource being scheduled?
  • What is the scheduling policy and where is it defined?

 What is coarse-grain locking?

  • What effect does it have on program complexity?
  • What effect does it have on performance?
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CS533 - Concepts of Operating Systems

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CS533 - Concepts of Operating Systems

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Questions

 What is “lock contention”?

  • Why is it worse on multiprocessors than uniprocessors?
  • What is the solution? … and its cost?

 What else might cause performance to degrade

when you use multiple threads?

 Why is multithreaded programming hard?

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Which style is used in modern OSs?

 Are modern operating systems (such as Linux)

written in an event-based or multi-threaded style?

 How does event-based programming relate to

interrupt handling?

 Where is the boundary between interrupt handling

and thread execution?

  • How does this affect the approaches used for

synchronization?

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Concurrent Computation vs Concurrent Blocking

 How is the CPU scheduled:

  • In an event-based system?
  • In a thread-based system?

 How is live state managed across blocking I/O calls:

  • In an event-based system?
  • In a thread-based system?
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Managing Highly Concurrent I/O

 What is the problem with making thread allocation

decisions statically?

  • What is the Slashdot effect?

 Why is multi-threading not a good match for massive

concurrency?

  • Is web service embarrassingly parallel?
  • What is the problem with the thread-per request model?
  • Why does the event handling model help?
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Questions

 What is a thread pool?  Why do the following techniques help during heavy

load?

  • Thread pool resizing
  • Event batching
  • Adaptive load shedding

 Why does pipeline parallelism scale well?

  • Thread per stage vs thread per request

 What does it mean for a service to be “well

conditioned”?