Skip to main content

Book Exercise Lanes

This module's exercise system is book-driven plus hands-on. Use these local chunks and hands-on tasks for targeted volume after you have already learned the concept from the guide.

How To Use This Page​

  1. Finish the relevant concept page first.
  2. Do at least one paper trace from memory.
  3. Only then open the matching exercise lane.
  4. Keep a mistake log with tags such as confused fd with inode, wrong crash ordering, skipped directory fsync, dirty page not flushed, select used where epoll belongs, edge-triggered drain loop missing, or assumed close implies fsync.

Lane 1: The File Abstraction (inodes, directories, FDs)​

Use this lane when the issue is the three-layer kernel table model or directory semantics.

Target outcomes:

  • 8 stat/ls -li traces (inode number, link count changes) performed on real files
  • 4 fork + shared-FD drills with predicted and observed behavior
  • 2 directory-lookup traces from mount point to target inode

Lane 2: On-Disk Layout and Archetypes​

Use this lane when you cannot draw the on-disk structure or trace a read to an LBA.

Target outcomes:

  • 6 hand-drawn ext-style layouts with addresses and sizes
  • 4 read traces from inode + offset to LBA
  • 2 comparisons of ext vs LFS on the same workload (append-heavy, random-update-heavy)

Lane 3: Crash Consistency​

Use this lane when you cannot reason about post-crash state for multi-step operations.

Target outcomes:

  • 6 operations (append, overwrite, rename, unlink, mkdir, hard-link) with crash-state tables for naive, journaled, and COW
  • 4 written "worst case" crash narratives with recovery steps
  • 2 correct implementations of "durable atomic file replacement" pattern

Lane 4: I/O Models and Performance​

Use this lane when you cannot pick between blocking, epoll, and io_uring, or cannot measure I/O performance.

Target outcomes:

  • a single-threaded epoll echo server handling 1k+ connections
  • a measurement report of fsync cost across at least 4 modes
  • a short comparison of select, epoll, and io_uring from your own run, with CPU and throughput numbers
  • 2 written debugging narratives from strace, iostat, or blktrace on your own workload

Self-Curated Problem Set​

Build a custom set with these minimums:

  • 5 crash-consistency scenarios across naive / journaled / COW
  • 5 layout tracing exercises (inode + offset -> LBA)
  • 5 fork / dup / open behavior predictions, verified in code
  • 5 I/O performance measurement tasks (cache-hot, cache-cold, sequential, random, fsync on/off)
  • 3 server builds (thread-per-conn, epoll, io_uring) and a comparison

Completion Checklist​

  • Completed at least one lane in full
  • Built the FUSE FS kata
  • Built the epoll echo server kata
  • Produced the fsync-cost table kata
  • Produced the crash-recovery simulator kata
  • Logged at least 10 real mistakes and corrections
  • Read strace, iostat, or blktrace output on your own workload at least twice