processor management
TRANSCRIPT
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Prepared By : Devang Vyas(14501002)
Processor Management
And Device Manager
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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
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Processor Manager
Job Scheduling
Process Scheduling
Interrupt Management
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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?
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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
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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
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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
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First Come First Served (FCFS) Shortest Job Next (SJN) Priority Scheduling Shortest Remaining Time (SRT) Round Robin Multiple Level Queues
Process Scheduling Algorithms
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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.
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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
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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
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I/o devices
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Device Manager
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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
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There are two way of Communication :- Serial/Parallel Synchronous/Asynchronous
Way of Communication
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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
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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
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Synchronous/Asynchronous
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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
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Thank You…..