D-SP-Ch14a-Nonblocking

Introduction

Slow System Call

D-SP-Ch14aa-Slow_System_Call

Introduction

The OS only reads or writes as many bytes as possible without context switch. This means:

1. We only write until the buffer cache is full then return
2. We only read data that is already in the buffer cache then return

After return, the OS will automatically move the required data from disk to buffer so that the next request can continue read/write

How to set to nonblocking?

open() or fcntl with O_NONBLOCK flag