Agenda
- How does the OS provide concurrency through threads
- Brief discussion of process/thread states and scheduling
- High-level discussion of how stacks contribute to concurrency
- Introduce needs for synchronization
- Discussion of Locks and Semaphores
Processes Multiplexing
The Process Control Block
- A chunk of memory in the Kernel represents each process as a process control block (PCB)
- Status (running, ready, blocked, …)
- Register state (when not running)
- Process ID (PID), User, Executable, Priority, …
- Execution time, …
- Memory space, translation, …
- Kernel Scheduler maintains a data structure containing the PCBs
- Give out CPU to different processes (who gets the CPU to run themselves!)
- This is a Policy Decision
- Give out non-CPU resources
- Memory/IO
- Another policy decision
Context Switch
Resources
