Module 1: Processes & Scheduling: Mistake Clinic

This clinic turns wrong moves into reusable judgment. Use it after each practice page and again before the quiz or checkpoint.

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Module-Specific Mistake Radar

Start with these traps. Replace or extend them with real mistakes from your own work.

Mistake to look for	Where it shows up	Symptom	Repair evidence
Finishing Scheduling Policy Lab with only a final answer	Scheduling Policy Lab	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Process Model Workshop with only a final answer	Process Model Workshop	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Context Switch Clinic with only a final answer	Context Switch Clinic	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Code Katas with only a final answer	Code Katas	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Treating The Process Abstraction: Address Space, Registers, PC as vocabulary instead of a tool	The Process Abstraction: Address Space, Registers, PC	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.
Treating The Process Control Block and Kernel State as vocabulary instead of a tool	The Process Control Block and Kernel State	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.

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Practice Mistake Checks

Pull any miss from these checks into your mistake log.

Scheduling Policy Lab

Source: practice/01-scheduling-policy-lab.md

Identify the error in each statement:

1. "Round-Robin is always fairer than SJF because it gives everyone a turn."
2. "SJF is the best policy for interactive systems."
3. "Throughput and average turnaround time are the same metric in different units."
4. "A smaller quantum always improves responsiveness."
5. "MLFQ is just Round-Robin with multiple queues."

Process Model Workshop

Source: practice/02-process-model-workshop.md

Identify the error:

1. "After fork(), the child has its own stack, so changes there affect the parent too."
2. "fork() always copies the entire parent address space immediately."
3. "The PCB lives in the process's own memory."
4. "A process in the BLOCKED state is using CPU."
5. "A zombie is a running process you cannot kill."
6. "After exec, the program counter is wherever it was before exec was called."

Context Switch Clinic

Source: practice/03-context-switch-clinic.md

Identify the error:

1. "A context switch just saves and restores registers."
2. "Switching between threads of the same process costs the same as switching between processes."
3. "An ASID-capable CPU never has to flush the TLB on a context switch."
4. "Interrupts are the only way to force a context switch."
5. "The scheduler picks the next task before the trap into the kernel."
6. "Threads share the stack."

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Repair Protocol

For each real mistake:

1. Reproduce the failure on the smallest example, trace, proof, query, command, or design sketch.
2. Name the hidden assumption.
3. Repair the artifact.
4. Save evidence that changed: failing then passing test, corrected proof step, revised diagram, safer command, benchmark, or review note.
5. Add one retrieval card beginning with Check... before... or Do not use... when....

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Mistake Log

Date	Mistake	Symptom	Root cause	Repair evidence	Retrieval card
Starter	Pick one radar row above	Explain how it would fail in this module	Name the assumption	Add a counterexample or corrected artifact	Write the card before closing the page

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Completion Standard

• At least five real mistakes are logged.
• At least two mistakes include a counterexample or failing test.
• At least one mistake connects to an older semester skill.
• At least one correction changes code, a proof, a diagram, a command transcript, a query, or a design decision.