問題一覧
1
An operating system executes a variety of programs. what are they?
batch system and time-shared systems
2
Terms ____ and ______ almost interchangeably
job, process
3
a program in execution which must progress in sequential fashion
process
4
______________________ started via GUI mouse clicks, command line entry of its name, etc
execution of program
5
A process, sometimes known as the _________, also includes the current activity represented by the value of the program counter.
text section
6
Contains the temporary data, such as function parameters, returns addresses, and local variables.
stack
7
Contains the global variable.
data section
8
Dynamically allocated memory to process during its run time.
heap section
9
As a process executes, it changes state.
process state
10
what includes the process state?
new, running, waiting, ready, terminated, suspended ready, suspended block
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The process is being created
new
12
Instructions are being executed
running
13
The process is waiting for some event to occur
waiting
14
The process is waiting to be assigned to a processor
ready
15
The process has finished execution
terminated
16
When the ready queue becomes full, some processes are moved to this state.
suspended ready
17
When waiting queue becomes full.
suspended block
18
what are the two things that needs to be considered for a process to move from different states in an operating system?
execution status and resource availability
19
When a process is created, it is in a new state. It moves to the ready state when the operating system has allocated resources to it and it is ready to be executed.
new to ready
20
When the CPU becomes available, the operating system selects a process from the ready queue depending on various scheduling algorithms and moves it to the running state.
ready to running
21
Information associated with each process (also called task control block)
process control block (PCB)
22
running, waiting, etc
process state
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location of instruction to next execute
program counter
24
contents of all process-centric registers
cpu registers
25
priorities, scheduling queue pointers
cpu scheduling information
26
memory allocated to the process
memory-management information
27
CPU used, clock time elapsed since start, time limits
accounting information
28
I/O devices allocated to process, list of open files
I/O status information
29
The process of saving the context of one process and loading the context of another process is known as _________. In simple terms, it is like loading and unloading the process from running state to ready state.
context switching
30
A ___________ occurs when CPU privilege level is changed, for example when a system call is made or a fault occurs. The kernel works in a more privileged mode than a standard user task.
mode switch
31
If a user process wants to access things which are only accessible to the kernel, a _________ must occur. The currently executing process need not to be changed during a mode switch.
mode switch
32
A _______________ requires more CPU time or spends more time in the running state, while an I/O-bound process requires more I/O time and less CPU time.
CPU-bound process
33
An _________ spends more time in the waiting state.
I/O bound process
34
__________ occurs when the exit system is called. A process usually exits after its completion but sometimes there are cases where the process aborts execution and terminates.
process termination
35
Process executes last statement and then asks the operating system to delete using the ______ system call.
exit()
36
Parent may terminate the execution of children processes using the _______ system call.
abort()
37
A thread is a basic ________________
unit of CPU utilization
38
A thread is a ___________ within a process code, with its own program counter that keeps track of which instruction to execute next, system registers which hold its current working variables, and a stack which contains the execution history.
path of execution
39
benefits of thread
responsiveness, resource sharing, economy, scalability
40
may allow continued execution if part of process is blocked, especially important for user interfaces
responsiveness
41
threads share resources of process, easier than shared memory or message passing
resource sharing
42
cheaper than process creation, thread switching lower overhead than context switching
economy
43
process can take advantage of multiprocessor architectures
scalability
44
- Many user-level threads mapped to single kernel thread - One thread blocking causes all to block - Multiple threads may not run in parallel on multicore system because only one may be in kernel at a time
many-to-one
45
- Each user-level thread maps to kernel thread - Creating a user-level thread creates a kernel thread - More concurrency than many-to-one - Number of threads per process sometimes restricted due to overhead
one-to-one
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- Allows many user level threads to be mapped to many kernel threads - Allows the operating system to create a sufficient number of kernel threads
many-to-many
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Similar to M:M, except that it allows a user thread to be bound to kernel thread
two-level model
48
- Windows implements the Windows API – primary API for Win 98, Win NT, Win 2000, Win XP, and Win 7 - Implements the one-to-one mapping, kernel-level
windows thread
49
The register set, stacks, and private storage area are known as the ______ of the thread
context
50
includes pointer to process to which thread belongs and to KTHREAD, in kernel space
ETHREAD (executive thread block)
51
scheduling and synchronization info, kernel-mode stack, pointer to TEB, in kernel space
KTHREAD (kernel thread block)
52
thread id, user-mode stack, thread-local storage, in user space
TEB (thread environment block)
53
Linux refers to them as _____ rather than threads
tasks
54
Thread creation is done through _______ system call
clone()
55
______ allows a child task to share the address space of the parent task (process)Flags control behavior
clone()
56
____________ points to process data structures (shared or unique)
struct task_struct
57
A process may be created by another process using ________. The creating process is called the parent process and the created process is called the child process.
fork()