Operating Systems

Process Hierarchies

Process Session
- Process Group
  - Process

Inter-Process Communications

Signal
Shared Memory
Message Passing
Memory-Mapped File

Synchronization Mechanisms

Atomic Instructions:
- test-and-set
- fetch-and-add
- compare-and-swap
Mutual Exclusions:
- Spin lock
- Lock (Mutex)
- Semaphore
- Read-Write Lock
- Condition Variable
- Monitor
- Barrier
- Message-Passing

Computer Architecture

Cache
- Locality:
  - Spatial Locality
  - Temporal Locality
Memory:
- SRAM: static, 6 transistors per bit, fast, less power, more expensive
- DRAM: dynamic, 1 transistor + 1 capacitor per bit, slow, requires refreshing
Storage Hierarchies:
- Registers --> Cache --> RAM --> SSD --> HDD
Parallelism:
- Instruction-Level:
  - Scalar Pipelining
  - Superscalar Pipelining
  - Out-of-Order Execution (Dynamic Scheduling)
- Thread-Level:
  - Coarse-Grain Multithreading
  - Fine-Grain Multithreading
- Process-Level:
  - Multicore --> Synchronization, Cache Coherency, Memory Consistency