MICROSOFT WINDOWS

ADMINISTRATION

Microsoft Windows Process Management

Introduction

Explain Microsoft Windows Process Management

• Multithreading

• Multiprocessing

• Multitasking

Process Management

• In computer science, a process is an application in execution.

• When a process is using the CPU, it is actually running and doing some work.

• However, it will not always stay in that state.

• If a process does I/O and the device is not ready or just slow, the process will become blocked and be unable to do any more work until the I/O is complete.

• In a multitasking environment, a process is not allowed to use the CPU all the time.

• At intervals (maybe signalled by a timer interrupt) it will be stopped by the O/S so that another process can run.

• In this state it is not running, but is runnable.

MULTITHREADING

• Multithreading computers have hardware support to efficiently execute multiple threads.

• The threads have to share the resources of single core: the computing units, the CPU caches.

The ability of an operating system to execute different parts of a program, called threads, simultaneously. The programmer must carefully design the program in such a way that all the threads can run at the same time without interfering with each other.

Advantages

• If a thread gets a lot of cache misses, the other threads can continue, taking advantage of the unused computing resources, which thus can lead to faster overall execution, as these resources would have been idle if only a single thread was executed.

Advantages

• If a thread can not use all the computing resources of the CPU (because instructions depend on each other's result), running another thread permits to not leave these idle.

Advantages

• If several threads work on the same set of data, they can actually share their cache, leading to better cache usage or synchronization on its values.

Disadvantages

• Multiple threads can interfere with each other when sharing hardware resources such as caches or translation lookaside buffers (TLBs).

Disadvantages

• Execution times of a single-thread are not improved but can be degraded, even when only one thread is executing. This is due to slower frequencies and/or additional pipeline stages that are necessary to accommodate thread-switching hardware.

Disadvantages

• Hardware support for Multithreading is more visible to software, thus requiring more changes to both application programs and operating systems than Multiprocessing.

Types of Multithreading

• Block multi-threading

• Interleaved multi-threading

• Simultaneous multi-threading

Threads

• Thread of execution results from a fork of a computer program into two or more concurrently running tasks.

• Thread is contained inside a process.

• Multiple threads can exist within the same process and share resources such as memory,

• While different processes do not share these resources.

MULTIPROCESSING

• 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.

• Multiprocessing sometimes refers to the execution of multiple concurrent software processes in a system

• However, the terms multitasking or multiprogramming are more appropriate to describe this concept.

• Multiprocessing is more appropriate to describe the use of multiple hardware CPUs.

• A system can be both multiprocessing and multiprogramming, only one of the two, or neither of the two.

Types of Multiprocessing

• Processor symmetry

• Instruction and data streams

• Processor coupling

MULTITASKING

• Multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU.

• In the case of a computer with a single CPU, only one task is said to be running at any point in time.

• Multitasking solves the problem by scheduling which task may be the one running at any given time.

• When another waiting task gets a turn.

• The act of reassigning a CPU from one task to another one is called a context switch.

• Even on computers with more than one CPU (called multiprocessor machines), multitasking allows many more tasks to be run than there are CPUs.

NTFS

• NTFS is the standard file system of Windows NT.

• including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7.

• NTFS supersedes the FAT file system as the preferred file system for Microsoft’s Windows operating systems.

• NTFS has several improvements over FAT and HPFS (High Performance File System)

• Such as improved support for metadata.

- The use of advanced data structures to improve performance, reliability,

- disk space utilization, plus additional extensions such as security access control lists (ACL) and file system journaling.

Versions

• NTFS has five released versions:

• v1.0 with NT 3.1, mid-1993

• v1.1 with NT 3.5, fall 1994

• v1.2 with NT 3.51 mid-1995 and NT 4 mid-1996 (occasionally referred to as "NTFS 4.0", because OS version is 4.0)

• v3.0 from Windows 2000 ("NTFS V5.0")

• v3.1 from Windows XP (autumn 2001; "NTFS V5.1"), Windows Server 2003 (spring 2003; occasionally "NTFS V5.2"), Windows Vista (mid-2005) (occasionally "NTFS V6.0") and Windows Server 2008

FAT

• File Allocation Table or FAT is a computer file system architecture now widely used on most computer systems and most memory cards, such as those used with digital cameras.

• It was developed by Bill Gates and Marc McDonald during 1976–1977.

• It is the primary file system for various operating systems including DR-DOS, FreeDOS, MS-DOS, OS/2 (v1.1) and Microsoft Windows (up until Windows Me).

• The FAT file system is relatively straightforward technically and is supported by virtually all existing operating systems for personal computers.

FAT Structures

• The FATxx volume is divided into four areas:

– The boot record

– The File Allocation Tables

– The root directory

– The data area

• The boot record is the first sector of a FAT12 or FAT16 volume, and the first 3 sectors of a FAT32 volume. It defines the volume, as well as the whereabouts of the other three areas. If the volume is bootable, then the first sector of the boot record also contains the code required to enter the file system and boot the OS.

• The File Allocation Table is a series of addresses that is accessed as a lookup table to see which cluster comes next, when loading a file or traversing a directory.

• The root directory is fixed in length and always located at the start of the volume.

• The data area fills the rest of the volume, and is divided into clusters; it is here that the file data is stored.

Comparison of FAT32 and NTFS file systems

• FAT32 is more advanced than FAT12 and FAT16.

• But if you compare FAT32 and NTFS, you may find that NTFS file system has several improvements over FAT32, for example:

1. The capability to recover from some disk-related errors automatically which FAT32 doesn't have.

2. Improved support for larger hard disks.

3. Better security because you can use permissions and encryption to restrict access to specific files to approved user.

4. Faster access speed. NTFS minimizes the number of disk accesses required to find a file.

• Generally speaking, NTFS is more powerful than FAT32 with improved access speed, performance, reliability, fault tolerance, recoverability, complicity, security, as well as support for long file names, large volumes.

• Furthermore, NTFS is the default file system for new installations of Windows Vista, and if you are upgrading from a previous version of Windows, you'll be asked if you want to convert your existing file systems to NTFS.