CSCI 109 Discussion 8 - Utilization how much useful work...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
CSCI 109 Discussion March {10,11}, 2016
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
'&,nnouncement Midterm 2 March 23 (Wednesday after spring break) SAL 101, 9AM 20% of final grade More difficult than midterm 1 Presentation Today: Operating Systems Next group: Networks {3/31, 4/1}
Image of page 2
'&,genda Presentation! Operating Systems (OS) OS overview Memory management Process scheduling
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
'&,ttendance
Image of page 4
Operating Systems
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
7Learning ,2Goals ±incl° lectures² 1. Know the difference between the CPU, the kernel, and the operating system 2. Explain why scheduling is important 3. Explain how several different scheduling algorithms work, and their advantages and disadvantages (FIFO, Shortest-remaining time, Round-robin (long timer and short timer), Priority) 4. Understand what memory fragmentation and paging are, and how the latter can be used to prevent the former 5. Name some of the functions of an operating system
Image of page 6
OS overview Intermediary between user and hardware The core of OS is called kernel Resource controller CPU time scheduling Memory space paging/segmentation I/O Devices File storage … and more
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
8Memory 8Management Allocate a contiguous region of memory space to a process Memory is too small to fit all processes Considerations: How do we know which part of memory is free to use? How to decide which process can access which part of memory? How to prevent malicious programs from accessing the part of memory that stores important information (e.g. kernel code)?
Image of page 8
+1Fragmentation Happens when allocated memory is freed (i.e. when processes complete) Blocks of memory are made available again, but they are not necessarily contiguous New process wants S3 contiguous memory S1 < S3 < S1 + S2 but we can’t allocate! Poor memory utilization
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Paging Part of modern virtual memory systems Allows memory to be non-contiguous Present a logically contiguous memory space the physical addresses are distributed across memory Divide both logical/physical address into “ pages ” (fixed size) page table: map from logical address to physical address Logical address Physical address
Image of page 10
Paging One way to deal with memory fragmentation freed memory space are always complete pages can be easily reused by kernel Still has internal fragmentation problem not every process will use up all memory space allocated design tradeoff between page table size & internal fragmentation
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The 6Kernel and Scheduling The core of the operating system is called the [KKUU^KKU\ One of its main responsibilities is to control access to resources (memory, I/O, and CPU time) Controlling access to CPU time is called VIISNXKKUJJTX\OY^MW
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern