1. CGS 3763 Operating Systems Concepts Spring 2013
Dan C. Marinescu
Office: HEC 304
Office hours: M-Wd 11: :30 AM

2. Lecture 9 – Monday, January 28, 2013
Last time:
Interrupts
Problem 2.8 from Chapter 2
Today:
Answers to student questions
Interrupt processing
Kernel data structures for process management
Next time
Creation and termination of processes
Inter-process communication
Shared memory
Message passing
Reading assignments
Chapters 3 and 4 of the textbook
Chapters 3 and 4 textbook slides
HW1 due on Wednesday
11/20/2018

3. Student questions from week 2
Jan 14th Monday:
A lot of people seem to have trouble understanding how things work physically. There are a lot of people asking, “Where are the registers,” or “Where is the cache,” etc. It would be really helpful if we could see more pictures with labels, or more diagrams in class of some of these things.
What is the purpose of abstraction?
Is a thread part of a process or independent? How do threads work?
Further explanation of hardware and software events.
Further explanation of addresses as well.
Cover in more detail what an abstraction is and Instruction Set Architecture.
I also didn’t understand the difference between 32 and 64 bit operating systems.
11/20/2018

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7. Storage hierarchy
11/20/2018

8. Multi-level storage
11/20/2018

9. Caching
Important principle, performed at many levels in a computer (in hardware, operating system, software)
Information in use copied from slower to faster storage temporarily
Faster storage (cache) checked first to determine if information is there
If it is, information used directly from the cache (fast)
If not, data copied to cache and used there
Cache smaller than storage being cached
Cache management important design problem
Cache size and replacement policy
11/20/2018

10. 11/20/2018

11. Student questions from week 2 (cont’d)
Jan 16th Wednesday:
What are MIPS and MFLOPS? Why are we interested in certain types of performance measurements over others for hardware (such as measuring CPU performance in MIPS or MFLOPS and no other measurements?
What is a type of interrupt?
What is context switching and what is its main purpose?
I would like more explanation of cache and it’s forms (ex. L1 cache) and how they are used in a system
Jan 18th Friday:
I would like an example of a problem that a computer cannot solve. Explain more about Universal computers.
11/20/2018

12. Examples of non-computable functions
The truth function, which correctly labels the statements of arithmetic as true or false, is not computable.
The halting problem function, which correctly labels program-input pairs as halting or non-halting, is easy to describe, but not computable.
The Tiling function, which given any finite set of polygonal tiles, outputs the size k of the largest k×k sqaure that can be tiled by them, or 0 if they tile the entire plane.
The Conjugate function, which given two words in a finite group presentation, correctly states whether they are conjugate or not.
11/20/2018

13. MIPS and MFLOPS
The speed of a processor is measured in number of operations per second.
There are two types of arithmetic operations and two distinct instruction execution units
Integers  MIPS (Million Instructions Per Second)
Floating point  MFLOPS (Million Floating Point Instructions Per Second)
11/20/2018

14. Interrupts  provide the means to react to internal and external events
11/20/2018

15. Context switching
The storing and restoring the state (context) of a process so that execution can be resumed from the same point at a later time.
Enables multiple processes/threads to share a single CPU. 
11/20/2018

16. Process Control Block (PCB)

17. CPU Switch From Process to Process

18. Control data structure maintained by the kernel
To carry out its functions the kernel must maintain information about all objects in the system. For example:
Processes  Process Control Block (PCB)
Open files  File Control Block (FCB)
11/20/2018

19. Process Control Block (PCB)
The entry for a process contains the following information
Process state
Program counter
CPU registers
CPU scheduling information
Memory-management information
Accounting information
I/O status information

20. Process Control Block (PCB)

21. The state of a process
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22. Interrupt handlers are a component of the kernel
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25. Kernel functions for program execution
Process management
Scheduling and resource allocation
Interrupt handling
Error handling
11/20/2018

26. System calls for process control
Load
Execute
Create, terminate a process
Block a process, abort
Get process attributes/set process attributes
Allocate/deallocate memory for a process
11/20/2018

27. Process Scheduling Queues
Job queue – set of all processes in the system
Ready queue – set of all processes residing in main memory, ready and waiting to execute
Device queues – set of processes waiting for an I/O device
Processes migrate among the various queues