Operating Systems

The bootstrap program is stored in

The occurrence of an event is usually signalled by an from either hardware or software.

in asymmetric clustering one machine is in while the other is running the applications

beowulf clusters nodes use a set of software libraries to communicate with one another

increases CPU utilization by organizing jobs (code and data) so that the CPU always has one to execute

modern systems are driven

bit is added to the hardware of the computer to indicate the current mode
- kernel (0)
- user (1)

a timers period may be or

a program is a entity, like the contents of a file stored on disk, whereas a process is an entity

a single-threaded process has one specifying the next instruction to execute

when selecting the memory-management scheme you must take into account many factors but especially the design of the system

with multiprocessors each has its own local cache so when the value of something changes you must make sure that value is changed computer wide. this is called

most operating systems maintain a lot of user names and associated

tree is when a parent may have an unlimited number of children

tree is when a parent may have at most two children, which we term left child and the right child

tree, additionally requires an ordering between the parents two children in which left_child <= right_child

tree is when a tree containing n items as at most log(n) levels

takes data as input, performs a numeric operation on this data, and returns a numeric value

associates pairs using a hash function

is a string of n binary digits that can be used to represent the status of n items

is a collection of physically separate, possibly heterogeneous computer systems that are networked to provide users with access to the various resources that the system maintains

is a communication path between two or more systems

is the most common network protocol, and it provides the fundamental architecture of the Internet

is an operating system that provides features such as file sharing across the network, along with communication scheme that allows different processes on different computers to exchange messages

many of todays systems act as to satisfy requests generated by

provides a file-system interface where clients can create, update, read, and delete files

computing clients and servers are not distinguished from one another

in a system, the server is a bottleneck; but in a system, services can be provided by several nodes distributed throughout the network

is used when the source CPU type is different from the target CPU type

is a form of emulation in that the high-level language code is translated to native CPU instructions, emulating not another CPU but a theoretical virtual machine on which that language could run natively

is an operating system that is natively compiled for a particular CPU architecture runs within another operating system also native to that CPU

a is a cloud available vie the internet to anyone willing to pay for the services

a is a cloud run by a company for that company's own use

a is a cloud that includes both public and private cloud components

embedded systems almost always run operating systems

is when two or more processes read and write to a shared section of memory

is packets of information in predefined formats are moved between processes by the operating system

the specifies a set of functions that are available to an application programmer, including the parameters that are passed to each function and return values the program can expect

is a system program designed to aid the programmer in finding and correcting errors

operating system requirements are divided into two basic groups: and

are how to do something and are what will be done

a failure in the kernel is called a crash and information about it is saved in a

the operating can take a , a capture of the memory of the process, to be stored for later analysis

the operating system produces of system behaviour to try to find bottle necks

periodically samples the instruction pointer to determine which code is being executed. It can show stat trends but not individual activity.

after the OS is generated, it must be loaded into the kernel using a . This program is placed in ROM.

a system executes jobs, whereas a system has user programs, or tasks

as a program executes, it changes . The of a process is defined in part by the current activity of the process

it is important to know that only process can be running at a time, while can be ready or waiting

-management information - This information may include such items as the value of the base and limit registers and the page tables, or the segment tables, depending on the memory system used by the operating system.

information - This information includes the amount of CPU and real time used, time limits, account numbers, job process numbers, and so on

I/O information - This information includes the list of I/O devices allocated to the process, a list of open files, and so on

a process is a program that performs a single of execution. Many systems now have upgraded this to allow a program to run multiple of execution.

to meet the objective of time sharing, the selects an available process for the program execution on the CPU

the processes that are residing in main memory and are ready and waiting to execute are kept on a list called the .

a new process is put on the ready queue until it is selected for execution or

the operating system must select processes from the queues using an appropriate

some systems such as time sharing systems may introduce -term schedulers. The idea is that sometimes it is advantageous to remove a process from memory to reduce the degree of multiprogramming. Later the process can be reintroduced to memory and start off where they left off, in a process called .

when an interrupt occurs, the system needs to save the current of the process running on the CPU so that it can restore that context when processing is done

the process is a child of init and is responsible for creating additional processes that perform tasks on behalf of the kernel

the process is a child of init and is responsible for the managing clients that connect to a system using ssh

the process is also a child of init and it is used to manage clients that directly log onto the system

A process that is terminated, but whose parents do not call wait is called a process. All processes transition to this state briefly but are often resolved once wait() is called by the parent

If a parent terminates before a child, it can not call wait(), so the child process becomes and . Linux and Unix solve this problem by assigning to be the new parent of a child process whose parent prematurely terminates.