❖ Midterm: the week of May 11-16 (Monday? Wednesday?

https://haojian.github.io/DSC102SP24/static_files/presentations/5OSBasics.pdf

Abstraction of a Process

Process: A running program, the central abstraction in OS

• Started by OS when a program is executed by user
• OS keeps inventory of “alive” processes (Process List) and handles apportioning of hardware among processes

A query is a program that becomes a process

• A data system typically abstracts away process management because user specifies the queries / processes in system’s AP

High-level steps OS takes to get a process going:

1. Create a process (get Process ID; add to Process List)
2. Assign part of DRAM to process, aka its Address Space
3. Load code and static data (if applicable) to that space
4. Set up the inputs needed to run program’s main()
5. Update process’ State to Ready
6. When process is scheduled (Running), OS temporarily hands off control to process to run the show!
7. Eventually, process finishes or run Destroy

Virtualization of Hardware Resources

Each hardware resource is treated as a virtual entity that OS can divvy up among processes in a controlled way