Skill Metadata
skill_config:
version: "1.0.0"
category: systems
prerequisites: [cs-foundations]
estimated_time: "10-12 weeks"
difficulty: intermediate-advanced
parameter_validation: domain: type: string enum: [cpu, memory, os, network, database, distributed] required: true scale: type: string enum: [single, cluster, global] default: single
retry_config: max_attempts: 3 backoff_strategy: exponential initial_delay_ms: 500
observability: log_level: INFO metrics: [domain_usage, design_pattern_frequency]
---
## Quick Start
Master how modern computers actually work, from circuits to distributed systems.
### Digital Logic & CPU
**CPU Concepts**
- Instruction execution cycle
- Registers and cache hierarchy
- Pipelining
- Branch prediction
**Cache Memory**
- L1, L2, L3 hierarchy
- Temporal and spatial locality
- Cache lines and blocks
### Operating Systems
**Process Management**
- Process states and context switching
- Scheduling algorithms: FCFS, SJF, round-robin
**Memory Management**
- Virtual memory and paging
- Page tables and TLB
- Page replacement: LRU, optimal
**Concurrency**
- Race conditions and critical sections
- Mutual exclusion: locks, semaphores
- Deadlock: conditions, detection, recovery
### Networking
**OSI Model**
- Layer 1: Physical (signals, cables)
- Layer 2: Data Link (MAC, switching)
- Layer 3: Network (IP, routing)
- Layer 4: Transport (TCP, UDP)
**Protocols**
- HTTP/HTTPS: Web
- TCP: Reliable connection
- UDP: Fast connectionless
- DNS: Name resolution
### Distributed Systems
**CAP Theorem**
- Consistency: all nodes same data
- Availability: responds to requests
- Partition tolerance: survives splits
- Can guarantee only 2 of 3
**Consensus Algorithms**
- Paxos: proven consensus
- Raft: simpler consensus
---
## Troubleshooting
| Issue | Root Cause | Resolution |
|-------|------------|------------|
| High latency | Slow DB queries | Add indexes, cache |
| Memory exhaustion | Memory leak | Profile, fix leaks |
| Connection exhaustion | Pool too small | Increase pool size |
| Cascading failure | No circuit breaker | Add circuit breakers |
---
## Key Concepts
- **Latency**: Time to complete one task
- **Throughput**: Tasks completed per unit time
- **Scalability**: Performance with increasing load
- **Fault tolerance**: Reliability despite failures
---
## Interview Questions
- How do caches work?
- Explain virtual memory
- What is thrashing?
- Difference between TCP and UDP?
- How do transactions work?
- Design a system that scales to millions of users