This document discusses processes in Unix, Linux, and Windows operating systems. It defines a process as comprising an address space, program code and data, execution stack, program counter, processor registers, system resources, and other information. It describes how processes are represented in the OS through a process table and process control block. It covers the different process states of ready, running, and waiting. It also discusses how processes are created, terminated, and how their privileges are inherited from the creating user or process. The document provides examples of how processes are created in Unix/Linux using fork and exec system calls and waiting for a child process. It contrasts the process model with the thread model used in later Windows and Linux systems.
What is program and process .
Program execution flow .
Example of process generation .
Description of process .
Types of process .
Ways of run process .
How process is generated using fork() and execution .
Process life cycle .
Process tree .
Process states .
Load Averages .
For monitoring and managing linux process tools .
The second part of Linux Internals covers system calls, process subsystem and inter process communication mechanisms. Understanding these services provided by Linux are essential for embedded systems engineer.
It is an extended machine
Hides the messy details which must be performed
Presents user with a virtual machine, easier to use
It is a resource manager
Each program gets time with the resource
Each program gets space on the resource
UNIT II PROCESS MANAGEMENT
Processes-Process Concept, Process Scheduling, Operations on Processes, Interprocess Communication; Threads- Overview, Multicore Programming, Multithreading Models; Windows 7 - Thread and SMP Management. Process Synchronization - Critical Section Problem, Mutex Locks, Semophores, Monitors; CPU Scheduling and Deadlocks.
What is program and process .
Program execution flow .
Example of process generation .
Description of process .
Types of process .
Ways of run process .
How process is generated using fork() and execution .
Process life cycle .
Process tree .
Process states .
Load Averages .
For monitoring and managing linux process tools .
The second part of Linux Internals covers system calls, process subsystem and inter process communication mechanisms. Understanding these services provided by Linux are essential for embedded systems engineer.
It is an extended machine
Hides the messy details which must be performed
Presents user with a virtual machine, easier to use
It is a resource manager
Each program gets time with the resource
Each program gets space on the resource
UNIT II PROCESS MANAGEMENT
Processes-Process Concept, Process Scheduling, Operations on Processes, Interprocess Communication; Threads- Overview, Multicore Programming, Multithreading Models; Windows 7 - Thread and SMP Management. Process Synchronization - Critical Section Problem, Mutex Locks, Semophores, Monitors; CPU Scheduling and Deadlocks.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
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Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
1. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 1
Processes in
Unix, Linux, and Windows
CS-3013, Operating Systems
A-term 2009
(Slides include materials from Modern Operating Systems, 3rd ed., by Andrew Tanenbaum and from
Operating System Concepts, 7th ed., by Silbershatz, Galvin, & Gagne)
2. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 2
Processes in Unix, Linux, and Windows
• In previous topic, we used “process” in a
generic way to represent the abstraction of
concurrency
• Unix pre-empted generic term “process” to
mean something very specific
• Linux and Windows adopted Unix definition
3. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 3
Process in Unix-Linux-Windows
comprises
• an address space – usually protected and virtual – mapped
into memory
• the code for the running program
• the data for the running program
• an execution stack and stack pointer (SP); also heap
• the program counter (PC)
• a set of processor registers – general purpose and status
• a set of system resources
– files, network connections, pipes, …
– privileges, (human) user association, …
• …
4. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 4
Reading Assignment
• Tanenbaum, §2.1
– Also §10.3.1, 10.3.2
5. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 5
Process Address Space (traditional Unix)
0x00000000
0xFFFFFFFF
(Virtual)
address space
program code
(text)
static data
heap
(dynamically allocated)
stack
(dynamically allocated)
PC
SP
6. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 6
Processes in the OS – Representation
• To users (and other processes) a process is
identified by its Process ID (PID)
• In the OS, processes are represented by entries in a
Process Table (PT)
– PID is index to (or pointer to) a PT entry
– PT entry = Process Control Block (PCB)
• PCB is a large data structure that contains or
points to all info about the process
– Linux – defined in task_struct (over 70 fields)
• see include/linux/sched.h
– Windows XP – defined in EPROCESS – about 60 fields
7. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 7
Processes in the OS – PCB
• Typical PCB contains:
– execution state
– PC, SP & processor registers – stored when
process is not in running state
– memory management info
– privileges and owner info
– scheduling priority
– resource info
– accounting info
8. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 8
Process – starting and ending
• Processes are created …
– When the system boots
– By the actions of another process (more later)
– By the actions of a user
– By the actions of a batch manager
• Processes terminate …
– Normally – exit
– Voluntarily on an error
– Involuntarily on an error
– Terminated (killed) by action of
• a user or
• another process
9. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 9
Processes – States
• Process has an execution state
– ready: waiting to be assigned to CPU
– running: executing on the CPU
– waiting: waiting for an event, e.g. I/O
10. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 10
Processes – State Queues
• The OS maintains a collection of process state
queues
– typically one queue for each state – e.g., ready, waiting,
…
– each PCB is put onto a queue according to its current
state
– as a process changes state, its PCB is unlinked from one
queue, and linked to another
• Process state and the queues change in response to
events – interrupts, traps
11. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 11
Processes – Privileges
• Users are given privileges by the system
administrator
• Privileges determine what rights a user has
for an object.
– Unix/Linux – Read|Write|eXecute by user,
group and “other” (i.e., “world”)
– WinNT – Access Control List
• Processes “inherit” privileges from user
– or from creating process
12. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 12
Process Creation – Unix & Linux
• Create a new (child) process – fork();
– Allocates new PCB
– Clones the calling process (almost exactly)
• Copy of parent process address space
• Copies resources in kernel (e.g. files)
– Places new PCB on Ready queue
– Return from fork() call
• 0 for child
• child PID for parent
13. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 13
Example of fork( )
int main(int argc, char **argv)
{
char *name = argv[0];
int child_pid = fork();
if (child_pid == 0) {
printf("Child of %s sees PID of %dn",
name, child_pid);
return 0;
} else {
printf("I am the parent %s. My child is %dn",
name, child_pid);
return 0;
}
}
_______________________________
% ./forktest
Child of forktest sees PID of 0
I am the parent forktest. My child is 486
14. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 14
Starting New Programs
• Unix & Linux:–
– int exec (char *prog, char **argv)
– Check privileges and file type
– Loads program at path prog into address space
• Replacing previous contents!
• Execution starts at main()
– Initializes context – e.g. passes arguments
•*argv
– Place PCB on ready queue
– Preserves, pipes, open files, privileges, etc.
15. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 15
Executing a New Program
(Linux-Unix)
• fork() followed by exec()
• Creates a new process as clone of previous
one
• I.e., same program, but different execution of it
• First thing that clone does is to replace itself
with new program
16. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 16
Fork + Exec – shell-like
int main(int argc, char **argv)
{ char *argvNew[5];
int pid;
if ((pid = fork()) < 0) {
printf( "Fork errorn“);
exit(1);
} else if (pid == 0) { /* child process */
argvNew[0] = "/bin/ls"; /* i.e., the new program */
argvNew[1] = "-l";
argvNew[2] = NULL;
if (execve(argvNew[0], argvNew, environ) < 0) {
printf( "Execve errorn“);
exit(1); /* program should not reach this point */
}
} else { /* parent */
wait(pid); /* wait for the child to finish */
}
}
17. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 17
Waiting for a Process
• Multiple variations of wait function
• Including non-blocking wait functions
• Waits until child process terminates
• Acquires termination code from child
• Child process is destroyed by kernel
• Zombie:– a process that had never been waited for
• Hence, cannot go away!
• See Love, Linux Kernel Development, pp 37-38
• See Tanenbaum, §10.3.2
18. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 18
Processes – Windows
• Windows NT/XP – combines fork & exec
– CreateProcess(10 arguments)
– Not a parent child relationship
– Note – privileges required to create a new
process
– See Tanenbaum, §11.4
– (More in this section than we have discussed so far)
19. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 19
Traditional Unix
• Processes are in separate address spaces
• By default, no shared memory
• Processes are unit of scheduling
• A process is ready, waiting, or running
• Processes are unit of resource allocation
• Files, I/O, memory, privileges, …
• Processes are used for (almost) everything!
20. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 20
Windows and Linux
• Threads (next topic) are units of scheduling
• Threads are used for everything
21. Processes in Unix,
Linux, and Windows
CS-3013 A-term 2009 25
Reading Assignment
• Tanenbaum, §2.1 & §10.3.1–10.3.2