Processor management

{1Navrachna University

Prepared By : Devang Vyas(14501002)

Processor Management

And Device Manager

2Navrachna University

Index Sr. No Contents

1) Introduction

2) Job Scheduling VS Process Scheduling

3) Process Scheduling Algorithms

4) Cache Memory

5) Interrupts

6) List of I/O devices

7) Need of device manager

8) Way of communication

9) Serial /parallel

10) Synchronous/asynchronous


Processor Manager

Job Scheduling

Process Scheduling

Interrupt Management


Process Manager performs job scheduling, process scheduling and interrupt management .

In single-user systems, processor is busy only when user is executing a job—at all other times it is idle.

Processor management is simple.

In multiprogramming environment, processor must be allocated to each job in a fair and efficient manner.

Requires scheduling policy and a scheduling algorithm

How Does Processor Manager Allocate CPU(s) to Jobs?


Processor Manager has 2 sub-managers:

1. Job Scheduler :- in charge of job scheduling.

2. Process Scheduler :- in charge of process scheduling.

Job Scheduling vs. Process Scheduling


Selects jobs from a queue of incoming jobs.

Places them in process queue (batch or interactive), based on each job’s characteristics.

Goal is to put jobs in a sequence that uses all system’s resources as fully as possible.

Strives for balanced mix of jobs with large I/O interaction and jobs with lots of computation. Tries to keep most system components busy most

of time.

Job Scheduler


Low-level scheduler – assigns the CPU to execute processes of those jobs placed on ready queue by Job Scheduler.

After a job has been placed on the READY queue by Job Scheduler, Process Scheduler that takes over. Determines which jobs will get CPU, when, and for

how long. Decides when processing should be interrupted. Determines queues job should be moved to during

execution. Recognizes when a job has concluded and should

be terminated.

Process Scheduler


First Come First Served (FCFS) Shortest Job Next (SJN) Priority Scheduling Shortest Remaining Time (SRT) Round Robin Multiple Level Queues

Process Scheduling Algorithms


Cache Memory

Cache memory -- quickly accessible memory that’s designed to alleviate speed differences between a very fast CPU and slower main memory.

Stores copy of frequently used data in an easily accessible memory area instead of main memory.

This memory is typically integrated directly with the CPU chip or placed on a separate chip that has a separate bus interconnect with the CPU.


Cache memory is fast and expensive. Traditionally, it is categorized as "levels" that describe its closeness and accessibility to the microprocessor:

Level 1 (L1) cache is extremely fast but relatively small, and is usually embedded in the processor chip (CPU).

Level 2 (L2) cache is often more capacious than L1; it may be located on the CPU or on a separate chip or coprocessor with a high-speed alternative system bus interconnecting the cache to the CPU, so as not to be slowed by traffic on the main system bus.

Level 3 (L3) cache is typically specialized memory that works to improve the performance of L1 and L2. It can be significantly slower than L1 or L2, but is usually double the speed of RAM. In the case of multicore processors, each core may have its own dedicated L1 and L2 cache, but share a common L3 cache.

Cache Memory Level


There are instances when a job claims CPU for a very long time before issuing an I/O request. builds up READY queue & empties I/O queues. Creates an unacceptable imbalance in the system.

Process Scheduler uses a timing mechanism to periodically interrupts running processes when a predetermined slice of time has expired. suspends all activity on the currently running job

and reschedules it into the READY queue.

Interrupts


I/o devices


Device Manager


The Device Manager is a Control Panel applet in Microsoft Windows operating systems.

It allows users to view and control the hardware attached to the computer.

When a piece of hardware is not working, the offending hardware is highlighted for the user to deal with.

The list of hardware can be sorted by various criteria.

Need of Device Manager


There are two way of Communication :- Serial/Parallel Synchronous/Asynchronous

Way of Communication


Serial/parallel

• serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus.

• Devices :- Keyboard, Mouse


When you turn the computer on, the motherboard executes a piece of code called the BIOS that is stored in a chip on the motherboard.

The BIOS knows how to find and communicate with the keyboard, and you can use the keyboard to configure the motherboard.

The operating system will then use routines in the BIOS to get keystrokes from the keyboard.

Bios :-BIOS (basic input/output system) is the program a personal computer's microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer's operating system and attached devices such as the hard disk, video adapter, keyboard, mouse and printer.

Working of Key-board


Synchronous/Asynchronous


Synchronous serial communication describes a serial communication protocol in which "data is sent in a continuous stream at a constant rate.

Synchronous :- Communication Does not Complete until the message has been received.

Asynchronous :- Completes as soon as the message is “on its way", and hopefully it gets to destination.

Synchronous/Asynchronous


Thank You…..

Technology

Processor management