Processes and Threads

• Difference Between Process and Thread - Georgia Tech - Advanced Operating Systems https://www.youtube.com/watch?v=O3EyzlZxx3g
  • Program is a set of instructions.
  • Thread: Line of control that courses through the core and data structures of a program, this is called a "thread of execution".
  • Process: Program and the state of all threads in the program
  • Newspaper example:
  • Newspaper = Program
  • Person A reading Sports section is a single thread
  • Person B reading Business section is a single thread
  • These threads can be competing for the same section or data structures to manipulate. The OS is the arbiter for competing requests and resources.
• Intro to Processes & Threads https://www.youtube.com/watch?v=exbKr6fnoUw
  • Single core CPU
  • Program is a set of instructions (binary code written for a specific CPU)
  • CPU has a Pipeline, Execution Engine, Math Processesor, etc. CPU runs on a clock (i.e. 2GHz)
  • System Memory (RAM) holds program before sending to CPU
  • Multi-threaded application
  • Threads are units of execution (Word app: Keyboard, Print, Save file)
  • Scheduler is a software switch that can switches between threads according to timeslice (1ms) and priority. The timeslice is so short that user believes it is simultaneous.
  • CPUs
  • Nowdays we have multi-tasking OS + multi-threaded applications
  • Hyperthreading split a CPU's Pipeline but would be blocked if threads encountered the Math Processor.
  • Multi-core CPUs have "cores" where each core has it's own Pipeline, Execution Engine, Math Processor, etc. This is where the industry has seemed to go.
  • Multi-CPU is the most powerful but is expensive. A lot of servers use multi-CPU.