System Building Rules & Tips from the OSTEP Book

15 Jun 2021 - Guanzhou Hu

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This short post is a summary list of all the system building tips/rules/laws boxes in the OSTEP book (also see my reading note). Without proper context, these tips make little sense, so I included the chapter numbers as well for easier back-tracing.

List of System Building Tips

• Use time-sharing and space-sharing (Chapter 4)
• Separate policy and mechanism (Chapter 4)
• “Get it right. Neither abstraction nor simplicity is a substitute for getting it right.” (Lampson’s law, Chapter 5)
• RTFM: read the manual pages (Chapter 5)
• Use protected control transfer (Chapter 6)
• Be wary of user inputs in secure systems (Chapter 6)
• Deal with application misbehavior (Chapter 6)
• Use interrupts to regain control (Chapter 6)
• Reboot is useful because it reverts the system to a known and likely correct state (Chapter 6)
• Shortest-job-first is a general scheduling principle (Chapter 7)
• Amortization can reduce costs (Chapter 7)
• Overlapping enables higher utilization (Chapter 7)
• Learn from history to make better decisions (Chapter 8)
• Scheduling also needs to be secure from attacks (Chapter 8)
• “Avoid voo-doo constants.” (Ousterhout’s Law, Chapter 8)
• Use advice where possible (Chapter 8)
• Use randomness when appropriate (Chapter 9)
• Use efficient data structures (Chapter 9)
• Remember the principle of isolation (Chapter 13)
• When in doubt, try it out (Chapter 14)
• It compiled/ran != it is correct (Chapter 14)
• Interposition is powerful (Chapter 15)
• Require hardware support if that’s better (Chapter 15)
• If 1000 solutions exist, no great one does; in this case, try to avoid the problem altogether (Chapter 16)
• Great engineers are really great (Chapter 17)
• Use caching when possible (Chapter 19)
• Use hybrid solution when appropriate (Chapter 20)
• Do work in the background (Chapter 21)
• Comparing against theoretical optimal is useful (Chapter 22)
• Be aware of the curse of generality (Chapter 23)
• Be lazy in certain cases (Chapter 23)
• Consider incrementalism (Chapter 23)
• Know and use available tools (Chapter 26)
• Use atomic operations (Chapter 26)
• Think in the way of a malicious scheduler when talking about concurrency bugs (Chapter 28)
• “Less code is often better code.” (Lauer’s Law, Chapter 28)
• More concurrency isn’t necessarily faster (Chapter 29)
• Be wary of control flow changes when using locks (Chapter 29)
• “Avoid premature optimization.” (Knuth’s law, Chapter 29)
• Always hold the lock while signaling (Chapter 30)
• Use while, not if, in multi-threaded program (Chapter 30)
• “Simple and dumb can be better.” (Hill’s law, Chapter 31)
• Be careful with generalization (Chapter 31)
• “Don’t always do it perfectly.” (Tom West’s law, Chapter 32)
• Don’t block in event-based servers. (Chapter 33)
• Interrupts not always better than polling. (Chapter 36)
• Be aware of disk sequentiality (Chapter 37)
• “It always depends.” (Livny’s law, Chapter 37)
• Transparency enables easier deployment (Chapter 38)
• Think carefully about naming (Chapter 39)
• Be wary of powerful commands (Chapter 39)
• TOCTTOU: time-of-check to time-of-use (Chapter 39)
• Consider extent-based approaches (Chapter 40)
• Reads don’t access allocation structures (Chapter 40)
• Understand static vs. dynamic partitioning (Chapter 40)
• Understand the durability/performance tradeoff (Chapter 40)
• Make the system usable (Chapter 41)
• Details matter (Chapter 43)
• Use a level of indirection when necessary (Chapter 43)
• Turn flaws into features (Chapter 43)
• Be careful with terminology (Chapter 44)
• The importance of backwards compatibility (Chapter 44)
• Sometimes the implementation shapes the interface (Chapter 44)
• TNSTAAFL: there is no free lunch (Chapter 45)
• Communication is inherently unreliable (Chapter 48)
• Use checksums for integrity (Chapter 48)
• Be careful setting the timeout value (Chapter 48)
• Idempotency is powerful (Chapter 49)
• “Perfection is the enemy of the good. Even in a beautiful system, there are corner cases.” (Voltaire’s law, Chapter 49)
• Innovaton breeds innovation (Chapter 49)
• “Measure, then build.” (Patterson’s law, Chapter 50)
• Crash consistency is not a panacea (Chapter 50)
• Understand the importance of workload (Chapter 50)
• Be careful of the weakest link (Chapter 53)
• Avoid storing secrets (Chapter 54)
• Privilege escalation is considered dangerous (Chapter 55)
• Don’t develop your own ciphers (Chapter 56)
• Infer implicit information if necessary (Appendix B)

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