D-OS-Ch05f-Thread_Scheduling

Thread Scheduling

Review

• user-level thread
• kernel-level thread
• scheduler activation

Introduction

現代 OS scheduling 的對象是 thread 而非 process

像是之前討論的 FCFS, SJF, Round-Robin 等演算法表面上說排程 process 實際上被排程的單位是 kernel-level thread

Contention Scope

Contention scope 指的是 thread 競爭的 CPU 範圍，分成兩個層次：

1. Process-Contention Scope (PCS)
2. System-Contention Scope (SCS)