Module 13 · From ScratchContainer Runtime

Container 04: /proc and /dev

Processes Threads and the Kernel — Processes Threads and the Kernel · Open board

The kernel’s table of processes. This stage mounts the window through which a program reads that table.

Before you start. Container 03: A Mount Namespace and pivot_root gave the box Alpine’s files and found that ps printed only its header. This stage fixes that. You need the idea of a mount from that lesson: a file system attached at a folder. The new idea is that some file systems are not stored on any disk. The kernel makes their files up on demand, so that a program can read the kernel’s state with the same cat and ls it uses for everything else. /proc is the main one (Processes, Threads & the Kernel names what it shows).

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Lab

The program needs twelve pages at once. What happens when it gets eleven frames?

Drag Frames of real memory from 24 down to 11, then back to 12, and watch Time spent working.

Open The working set →

Three long jobs are running when you press a key. How long until the keypress gets the CPU?

Click Take turns, drag How long one turn lasts from 100 ms down to 1 ms, and watch The keypress waits.

Open The time slice →

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