Linux System Process Management Introduction

Microsoft system process management, can not open the task manager, view the process, end the process, or create a process. But process management is a more complicated task in Linux systems. This article will introduce Linux process management in detail.

common scheduling algorithm

FCFS

First Come First Service. FIFO mode scheduling strategy, first come and then service mode.

The advantage of this approach is that it is simple and the easiest to think of. But there are two major problems:

1. It is not good for the operation of short processes.

Short processes must wait until the long process is completed before running, and may wait for a long time.

2. Unfavorable for IO-intensive operations

IO-intensive is worse than short-term processes. It's not easy to wait until he runs. The result is not running for a while because the IO is blocked. After the IO operation is completed, it has to be re-queued.

So this algorithm is extremely inefficient for IO-intensive processes.

RR

Round Robin. The polling scheduling algorithm allocates a fixed time slice for each process. After the time slice is used up, it must be re-queued to the end of the queue.

This design solves the first problem of FCFS, and partially solves the second problem.

But the IO-intensive process is still not well solved. There is an optimized solution for designing two queues. The process of IO blocking is placed in a separate queue, and when the next run is selected, The process of this queue is empowered.

Another complicating issue with FCFS is how to choose time slices. If the time slice is too long, it will degenerate into the FCFS algorithm. Too short will cause the switching overhead to be too large.

Prediction

Predictive based algorithms. This type of prediction algorithm assumes that we know the total time required for each process, as well as the IO ratio information. Previous12345Next page Total 5 pages