問題一覧
1
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
2
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
3
Dynamically allocated memory to process during its run time.
heap section
4
An _________ spends more time in the waiting state.
I/O bound process
5
Instructions are being executed
running
6
threads share resources of process, easier than shared memory or message passing
resource sharing
7
thread id, user-mode stack, thread-local storage, in user space
TEB (thread environment block)
8
- 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
9
Parent may terminate the execution of children processes using the _______ system call.
abort()
10
Contains the temporary data, such as function parameters, returns addresses, and local variables.
stack
11
When waiting queue becomes full.
suspended block
12
Thread creation is done through _______ system call
clone()
13
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()
14
Terms ____ and ______ almost interchangeably
job, process
15
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
16
may allow continued execution if part of process is blocked, especially important for user interfaces
responsiveness
17
The process has finished execution
terminated
18
I/O devices allocated to process, list of open files
I/O status information
19
priorities, scheduling queue pointers
cpu scheduling information
20
what includes the process state?
new, running, waiting, ready, terminated, suspended ready, suspended block
21
- 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
22
a program in execution which must progress in sequential fashion
process
23
Information associated with each process (also called task control block)
process control block (PCB)
24
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
25
memory allocated to the process
memory-management information
26
process can take advantage of multiprocessor architectures
scalability
27
benefits of thread
responsiveness, resource sharing, economy, scalability
28
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
29
As a process executes, it changes state.
process state
30
A process, sometimes known as the _________, also includes the current activity represented by the value of the program counter.
text section
31
The process is waiting to be assigned to a processor
ready
32
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
33
____________ points to process data structures (shared or unique)
struct task_struct
34
Linux refers to them as _____ rather than threads
tasks
35
Contains the global variable.
data section
36
cheaper than process creation, thread switching lower overhead than context switching
economy
37
An operating system executes a variety of programs. what are they?
batch system and time-shared systems
38
When the ready queue becomes full, some processes are moved to this state.
suspended ready
39
running, waiting, etc
process state
40
__________ 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
41
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
42
The process is waiting for some event to occur
waiting
43
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
44
scheduling and synchronization info, kernel-mode stack, pointer to TEB, in kernel space
KTHREAD (kernel thread block)
45
______________________ started via GUI mouse clicks, command line entry of its name, etc
execution of program
46
Process executes last statement and then asks the operating system to delete using the ______ system call.
exit()
47
includes pointer to process to which thread belongs and to KTHREAD, in kernel space
ETHREAD (executive thread block)
48
- 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
49
location of instruction to next execute
program counter
50
Similar to M:M, except that it allows a user thread to be bound to kernel thread
two-level model
51
The process is being created
new
52
______ allows a child task to share the address space of the parent task (process)Flags control behavior
clone()
53
CPU used, clock time elapsed since start, time limits
accounting information
54
A thread is a basic ________________
unit of CPU utilization
55
contents of all process-centric registers
cpu registers
56
- 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
57
The register set, stacks, and private storage area are known as the ______ of the thread
context