Wednesday, November 21, 2012

Advantage and disadvantage of multiprocessing? Command line vs. GUI , advantages and disadvantage of Linked Allocation and Indexed Allocation

1.    Advantage and disadvantage of multiprocessing?
Ans: Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor and/or the ability to allocate tasks between them.[1] There are many variations on this basic theme, and the definition of multiprocessing can vary with context, mostly as a function of how CPUs are defined.

1.increase throughput
2.Economy of scale
3. Increased reliability

1) If one processor fails then it will affect in the speed
2) multiprocessor systems are expensive
3) complex OS is required
4) large main memory requried.

4. Command line vs. GUI.
Users not familiar with a command line interface (CLI) or a graphic user interface (GUI) may want to know the advantages and disadvantages of each interface to help determine what interface is the best for them to use and why. Below is a table to help illustrate the major advantages and disadvantages of each of the interfaces.
Command line (CLI)
Because of the memorization and familiarity needed to operate a command line interface, new users have a difficult time navigating and operating a command line interface.
Although new users may have a difficult time learning to use the mouse and all GUI features, most users pick up this interface much easier when compared to a command line interface.
Users have much more control of their file system and operating system in a command line interface. For example, users can copy a specific file from one location to another with a one-line command.
Although a GUI offers plenty of control of a file system and operating system, the more advanced tasks may still need a command line.
Although many command line environments are capable of multitasking, they do not offer the same ease and ability to view multiple things at once on one screen.
GUI users have windows that enable a user to view, control, and manipulate multiple things at once and is much faster to navigate when compared with a command line.
Command line users only need to use their keyboards to navigate a command line interface and often only need to execute a few lines to perform a task.
A GUI may be easier to use because of the mouse. However, using a mouse and keyboard to navigate and control your operating system for many things is going to be much slower than someone who is working in a command line.
A computer that is only using the command line takes a lot less of the computers system resources than a GUI.
A GUI requires more system resources because of each of the elements that need to be loaded such as icons, fonts, etc. In addition, video drivers, mouse drivers, and other drivers that need to be loaded will also take additional resources.
A command line interface enables a user to script a sequence of commands to perform a task or execute a program.
Although A GUI enables a user to create shortcuts, tasks, or other similar actions, it doesn't even come close in comparison to what is available through a command line.
Remote access
When accessing another computer or networking device over a network, a user will only be able to manipulate the device or its files using a command line interface.
Although remote graphical access is possible. Not all computers and especially not all network equipment will have this ability.
After you've learned how to navigate and use a command line, it's not going to change as much as a new GUI. Although new commands may be introduced, the original commands always remain the same.
Each GUI has a different design and structure of how to perform different tasks. Even different versions of the same GUI, such as Windows, can have hundreds of different changes between each version.
The command line allows the user to keep their hands on the keyboard and rarely have to move from the keyboard to the mouse. Moving back and forth between a keyboard and mouse can cause additional strain and may help contribute to Carpal Tunnel.
Although shortcut keys can be learned to help reduce the amount of times you have move from the keyboard to the mouse, you will still be moving much more between the keyboard and mouse with a GUI.
Although it appears that a command line wins this comparison, it is not meant to be a suggestion to stop using a GUI such as Windows and only use a command line. It is more beneficial for a computer user to learn and understand both a GUI and CLI and know the strengths and weaknesses of each interface.

Linked Allocation
•  No external fragmentation
•  Files can be easily grown, with no limit
•  Cannot calculate random addresses w/o reading previous blocks
•  Sequential bandwidth may not be good
   –Try to allocate blocks of file contiguously for best performance

Indexed Allocation
• No external fragmentation
• Files can be easily grown, with no limit
• Supports random access
• Large overhead for meta-data:
–Wastes space for unneeded pointers (most files are small!)

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