Dijkstra "THE" - Multiprogramming System 笔记
好难读啊，后面提出了semaphore 的观念，非常关键。 之前提出了一堆 level, 是为了实现multiprogramming 应该不是第一次提出multiprogramming 的观念吧。 荷兰人的英语真是晦涩啊。 Background: Time: 1968 32K Memory 512K words drum Goal: Process smoothly a continuous flow of user programs System Hierarchy: -Level 0: Processor allocation, the interrupt of real clock is processed (kernel scheduling 应该发生在这个时候，避免一个process 独占CPU) -Level 1: Handle drum interrupt (应该试page-fault,做Memory Management) -Level 2 Console -Level 3 devices -Level 4 Application -Level 5 Operator Semaphore: -Definition: special purpose integer variables to ensure synchronization between parallel sequential processes. They're initialized before the parallel process start. Parallel process will acces the semaphores only via two very specific operations: primitives