Different Types Of Processes Computer Science Essay

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Processes in computing define as roughly a task being executed by a computer, often simultaneously with many other tasks. Many processes can coexist, but they need to turn on the CPU process and several process may be associated with the same program, for example, opening multiple instances of the same program often means more than one process is being execution.

Kernel-level threads

A kernel thread or LWP (Lightweight Process) is created and programmed by the kernel. Kernel threads are often more expensive than creating threads of user and system calls to create direct kernel threads are very specific platform.

User-level threads

A user-level thread includes a set of registers, a stack and it is sharing the whole address with the threads in the process. A user-level thread is handled in user code, by a special library that provides start, swap and suspend calls. Because the OS is not aware of the existence of a user-level thread, a thread-level user cannot receive signals separately or planning to use operating system calls like sleep.

Which of the alternatives will be the fastest?

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Efficiency and flexibility are the most primary advantages of user-level threads. User-level threads are also more flexible because the thread scheduler is in user code, which makes it much easier to schedule threads in an intelligent fashion. Because the operating system is not engaged, the discussions at the user level can be made to use little memory and can be programmed and created very quickly. Is normally a user thread created by a thread library and the programming is managed by the thread library itself. All user threads belong in this process has created. The advantage of user threads is that they are portable. User-Level Threads are also more flexible because the thread scheduler is in.

Since user code is controlling the user-level threads, there is no limit on the maximum number of threads as long as the resource allows. In real, one easily can create 50,000 user-level threads on a Linux.

Which of the alternatives will use the least memory and why?

A kernel thread is the "lightest" unit of kernel programming. At least one kernel thread exists within each process. If multiple kernel threads can exist within a process, then they share the same memory and file resources. Kernel threads are preemptively multitasking scheduler process if the operating system is preemptive. Kernel threads do not own resources except for a battery, a copy of records, including the program counter, and thread local storage.

One might expect the number of threads to be limited only by the address space and CPU time. Since every thread needs only a small battery and a data structure describing the thread, in principle, this limit must be no problem. Goal in practice, we found that many platforms impose hard limits on the maximum number of threads that can be created in a process.

Which of the alternatives is likely to produce the most robust and reliable system and Why?

A process consists of:

Memory contains executable code or task-specific data.

Operating system resources that are allocated to the process.

Security attributes.

Processor state, such as the content of registers, physical memory addresses.

The final processor state is associated with each of the process threads in operating systems that support threads. Time-sharing is the most common form of multitasking and it is a method to enable rapid response times for interactive user applications. These systems are done fast context switch and it seems like multiple processes running simultaneously on the same processor. It is called parallelism.

Most modern operating systems prevent direct communication between providing strictly mediated, independent processes and controlled inter-process communication for security and reliability reasons.

Task (2)

Process Name

Arrivals Time

Running Time

A

100

150

B

110

20

C

130

100

D

170

30

E

200

80

Priority of Process

Process

Arrival Time

Priority

A

100

3

B

110

5

C

130

1

D

170

4

E

200

2

Time

Process A

Process B

Process C

Process D

Process E

Process Complete

100

150

110

150

20

130

150

20

100

230

150

20

0

30

80

C Complete

310

150

20

0

30

0

E Complete

450

0

20

0

30

0

A Complete

490

0

20

0

0

0

D Complete

510

0

0

0

0

0

B Complete

Proper Order of the 5 Processes

Task (3)

Process

Allocated

Maximum

Difference

a

b

C

d

e

a

b

c

d

e

a

b

c

d

e

A

1

0

2

1

1

1

1

2

1

3

0

1

0

0

2

B

2

0

1

1

0

2

2

2

1

0

0

2

1

0

0

C

1

1

0

1

0

2

1

4

1

0

1

0

4

0

0

D

1

1

1

1

0

1

1

2

2

1

0

0

1

1

1

Process

Maximum

a

b

c

d

e

A

1

1

2

1

3

B

2

2

2

1

0

C

2

1

4

1

0

D

1

1

2

2

1

TOTAL

6

5

10

5

4

(A)

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Available Request = Maximum Required - Current Allocated

= ( 6 5 10 5 4 ) - ( 5 2 4 4 1 )

= ( 1 3 6 1 3 )

Checking Process A = ( 1 0 2 1 1 )

B can be completed as ( 0 1 0 0 2 ) less than or equal ( 1 3 6 1 3 )

Available = Available Request + Current Allocated

= ( 1 3 6 1 3 ) + ( 1 0 2 1 1 )

= ( 2 3 8 2 4 )

Compare = Maximum Required - Available

= ( 6 5 10 5 4 ) - ( 2 3 8 2 4 )

= ( 4 2 2 3 0 )

= Currently Safe State

Checking Process B = ( 2 0 1 1 0 )

B can be completed as ( 0 2 1 0 0 ) less than or equal ( 1 3 6 1 3 )

Available = Available Request + Current Allocated

= ( 1 3 6 1 3 ) + ( 2 0 1 1 0 )

= ( 3 3 7 2 3 )

Compare = Maximum Required - Available

= ( 6 5 10 5 4 ) - ( 3 3 7 2 3 )

= ( 3 2 3 3 1)

= Currently Safe State

Checking Process C = ( 1 1 0 1 0 )

B can be completed as ( 1 0 4 0 0 ) less than or equal ( 1 3 6 1 3 )

Available = Available Request + Current Allocated

= ( 1 3 6 1 3 ) + ( 1 1 0 1 0 )

= ( 2 4 6 2 3 )

Compare = Maximum Required - Available

= ( 6 5 10 5 4 ) - ( 2 4 6 2 3 )

= ( 4 1 4 3 1 )

= Currently Safe State

Checking Process D = (1 1 1 1 0)

D can be completed as (0 0 1 1 1) less than or equal (1 3 6 1 3)

Available = Available Request + Current Allocated

= (1 3 6 1 3) + (1 1 1 1 0)

= ( 2 4 7 2 3 )

Compare = Maximum Required - Available

= ( 6 5 10 5 4 ) - ( 2 4 7 2 3 )

= ( 4 1 3 3 1)

= Currently Safe State

Current system is safe but if one more resource is add to the last sequence of process A, deadlock will occur.

(B)

New Request = ( 1 0 1 0 1 )

New Current Allocated = Current Allocation + New Request

A = (1 0 2 1 1) + (1 0 1 0 1) = (2 0 3 1 1)

New Request = (0 0 0 4 4)

New Current Allocated = Current Allocation + New Request

A = (1 0 2 1 1) + (0 0 0 4 4) = (1 0 2 5 5)

If one more resource is add to the last sequence of process A on it column "e", deadlock will occur.

(C)

Add both of free C resources to process C = (1 1 11 5 4 )

Worst request = Maximum - New Process C Request

= (6 5 10 5 4 ) - ( 1 1 11 5 4 ) = ( 5 4 -1 0 0 )

Deadlock is possible because the maximum of the resources only can accept

( 6 5 10 5 4 ).

Task (4)

Windows Memory Management

Memory management of Microsoft Windows operating system has become a rich and complex structure, from small embedded platform scalable) until up to several TB of the NUMA configuration, while the hardware design of existing and future full use of all capacity.

With every version of Windows, memory management support many new features and capabilities. Advances in algorithms and techniques produce a rich and complex code base, which is maintained as a single code base for all platforms and SKUs.

Memory management improvements in Windows Vista has focused on areas such as dynamic system address space, improved NUMA and large system / site support, to support advanced video model, I / O and section access, and robustness.

Windows Server Disadvantages

Unlike UNIX, Windows Server is requiring a more system resources. You need a powerful computer to run Windows Server. The Windows server does not have a good renown in the name of the server stability. The Windows server must be restarted more often than UNIX. When using Windows Server hosting services. The costs of the applications that can run on your website are normally more higher than UNIX system. For example, you can run a lot of free scripts on the web board, chat room, web statistics, E-mail for your UNIX-based website, but you will not have many free applications in Windows server world.

Most common error that happens in windows memory management

Memory Leak

Some programs show continuous memory, without him, and eventually result from memory. This condition is known as memory loss.

External Fragmentation

Do a poor allocated can give and receive blocks of memory so bad that it is not sufficient enough additional memory blocks. This is because the free space can be divided into many blocks.

Read-only domain controllers

In Windows NT, only the primary domain controller could not and all backup domain controllers have been written to be read only. In Windows Server 2008, Microsoft has gone back to using this model, at least in part. Although Windows Server 2008 still uses the same model for domain controllers that are used in Windows Server 2003 and Windows 2000, it also supports a hardened read-only domain controller model.

As was the case with Windows NT Backup domain Controller, Read-Only domain Controller cannot be updated directly. You will only receive updates from a write able DC. Read-Only domain Controllers are ideal for stores, because the Active directory database is resistant to tinker.

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