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Operating System NachOS Project

Operating System NachOS Project. 教授：周立德 老師. 行動寬頻網路實 驗室 太空遙測研究中心 R3-305 分機： 57968 Email: kkw@networklab.csie.ncu.edu.tw. Outline. What is NachOS How does NachOS work Source Tree System Starting Install NachOS Projects Installation Multiprogramming Scheduling. What is NachOS.

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Operating System NachOS Project

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  1. Operating System NachOS Project 教授：周立德 老師 行動寬頻網路實驗室 太空遙測研究中心 R3-305 分機：57968 Email: kkw@networklab.csie.ncu.edu.tw

  2. Outline • What is NachOS • How does NachOS work • Source Tree • System Starting • Install NachOS • Projects • Installation • Multiprogramming • Scheduling

  3. What is NachOS • Not Another Completely Heuristic Operating System • Written by Tom Anderson and his students at UC Berkeley in 1992 http://www.cs.washington.edu/homes/tom/nachos/

  4. What is NachOS • An educational OS used to • Teach monolithic kernel design and implementation • Do experiments, you can (and will) modify and extend it • Fact • Real hardware is difficult to handle • May break if handled wrong

  5. What is NachOS • Approach • Use a virtual MIPS machine • Provide some basic OS elements • Includes many facets of a real OS: • Threads • Interrupts • Virtual Memory • I/O driven by interrupts

  6. What is NachOS • NachOS also contains some hardware simulation • MIPS processor • Can handle MIPS code in standard COFF, except for floating point instructions • You can (and will) write code in C/C++, compile it to MIPS and run it on NachOS • Console, Network interface, Timer

  7. How does NachOS work • Run as a single UNIX process • Provide a skeletal OS that supports • Threads • User-level processes • Virtual memory • Interrupt-driven I/O devices

  8. How does NachOS work • Two modes of execution • NachOS kernel • Executes when • NachOS starts up • A user-program causes a software trap (page fault, syustem call, etc.) • MIPS simulator • Initialized and started by NachOS kernel

  9. How does NachOS work

  10. How does NachOS work • Simulates MIPS architecture on host system (UNIX / Linux / Windows / MacOS X) • User programs need a cross-compiler (target MIPS) • NachOS appears as a single threaded process to the host operating system

  11. How does NachOS work

  12. How does NachOS work

  13. How does NachOS work

  14. Source Tree Root directory C++ introduction to teach how to write C++ Root directory of Nachos’s source code The tool to convert user programs from MIPS’s COFF into NachOS’s NOFF (NachOS Object File Format ) format File system Nachos’s library Source code of NachOS kernel and MIPS simulator MIPS machine In/Out message queues NachOS’s sample user programs threads User programs’ interfaces: system calls, address space,noffformat

  15. Start up interrupt handling initialize the ready queue and scheduler initialize MIPS machine Run some system testing System Starting > ./nachosstart code/threads/main.ccmain create kernel object initialize the system Invoke user program No user program Load user program System halt and terminate Run user program

  16. Install NachOS • Platform: Linux or Linux over VMware • RedHat Linux 9.0 • Install steps • Get NachOS-4.0 • wgethttp://140.115.155.199/2012_os/file/nachos-4.0.tar.gz • Get Cross Compiler • wget http://140.115.155.199/2012_os/file/mips-decstation.linux-xgcc.gz • Move Cross Compiler to / (根目錄) • mv ./mips-decstation.linux-xgcc.gz / • Untar Cross Compiler • cd / • tar zxvf /mips-decstation.linux-xgcc.gz

  17. Install NachOS • Untar NachOS-4.0 • tar zxvf ./nachos-4.0.tar.gz • Make NachOS-4.0 • cd ./nachos-4.0/code • make • Test if installation is succeeded • cd ./userprog • ./nachos -e ../test/test1 • ./nachos -e ../test/test2 • You should see the following…

  18. The test1 result Total threads number is 1 Thread ../test/test1 is executing. Print integer:9 Print integer:8 Print integer:7 Print integer:6 return value:0 No threads ready or runnable, and no pending interrupts. Assuming the program completed. Machine halting! Ticks: total 200, idle 66, system 40, user 94 Disk I/O: reads 0, writes 0 Console I/O: reads 0, writes 0 Paging: faults 0 Network I/O: packets received 0, sent 0

  19. The test2 result Total threads number is 1 Thread ../test/test2 is executing. Print integer:20 Print integer:21 Print integer:22 Print integer:23 Print integer:24 Print integer:25 return value:0 No threads ready or runnable, and no pending interrupts. Assuming the program completed. Machine halting! Ticks: total 200, idle 32, system 40, user 128 Disk I/O: reads 0, writes 0

  20. Operate NachOS • NachOS command help • ./nachos -h • Debugging mode • ./nachos -s • Execute files on NachOS • ./nachos -e ../test/test1

  21. Operate NachOS • 各個部分的編譯運行 • Nachos的各個部分都可以獨立編譯運行，也可以同時編譯各個部分。全部編譯可以採用如下命令： • code]# make • 當需要單獨編譯執行緒管理部分時，先進入threads目錄，然後採用如下命令： • threads]# make depend • threads]# make nachos

  22. Recompile Modified NachOS Code • cd nachos-4.0/code • make clean (optional) • make • If you want to fully re-compile the source code, “make clean” is required. Or make will only re-compile the modified and related files. (save time)

  23. Trace NachOS • Read *.h and *.cc to have an overview about the whole system and see how it is implemented • Documentation (A Road Map Through NachOS) • http://www.cs.duke.edu/~narten/110/nachos/main/main.html

  24. Project 1 - Installation • NachOS 介紹 • 安裝 NachOS，環境，過程 • 把安裝過程抓圖作成說明文件 (word 檔) • 利用Print Screen Button(請勿使用Alt+ Print Screen) • 把所有在 linux 下用到的指令解釋清楚其用法，並舉例說明

  25. Project 2 - Multiprogramming • 到 nachos-4.0/code/userprog 目錄下執行 • ./nachos –e ../test/test1 –e ../test/test2 Total threads number is 2 Thread ../test/test1 is executing. Thread ../test/test2 is executing. Print integer:9 Print integer:8 Print integer:7 Print integer:20 Print integer:21 Print integer:22

  26. Race Condition

  27. Project 2 - Multiprogramming • Please trace the following files to see why the output results are wrong • nachos-4.0/code/userprog/addrspace.h • nachos-4.0/code/userprog/addrspace.cc • nachos-4.0/code/userprog/userkernel.cc • nachos-4.0/code/machine/translate.h • Nachos-4.0/code/machine/translate.cc

  28. Project 2 - Multiprogramming • Please modified the Nachos code to run the correct results • You may need to modify the following functions • nachos-4.0/code/userprog/addrspace.cc

  29. Project 3 - Scheduling • Implement system call “Sleep” • Implement Multilevel Queue Scheduling (three Queue) • Non-preemptive Shortest-Job-First Scheduling (1 Queue) • First-Come, First-Served Scheduling (2 Queue) • Round-Robin Scheduling (3 Queue)

  30. System call “Sleep” • 請實作 Sleep(int x) 這個 system call, 把呼叫這個 system call 的 thread block住, 並且在 x 次的 timer interrupts 以後才又回到 READY 的狀態。

  31. System call “Sleep” (cont.) • 修改 exception.cc, syscall.h, start.s • 呼叫 alarm.cc 的 WaitUntil(int x) 來處理 Sleep(int x) 這個 system call

  32. SJF Scheduling • NachOS 內定的 scheduling algorithm 是 Round-Robin，請設計 non-preemptive SJF Scheduling • 請自行設計一組或多組 test case 來證明你的 project 是對的，針對 FCFS、RR 或是 SJF 都要能運作，放到 NachOS 下面去執行的 thread，每個Queue個數至少 3 個

  33. SJF Scheduling (cont.) • 由於是 non-preemptive，所以當 timer interrupts 時不用將 thread yield • 什麼時候有可能換 thread 執行？ • 需要記錄每個 thread 實際 CPU burst 長度 (timer interrupts 數目), 與預測將來 CPU burst 長度 • 在哪裡可以得到這個資訊？ • 何時該進行預測？

  34. Begin Running Invoke Sleep(x) Per timer interrupt: 1.Record actual CPU burst 2.叫醒應該起床的 threads 1.Set next predicted CPU burst 2.Insert this thread to Sleeping thread lists 3.Invoke thread->Sleep SJF Scheduling (cont.)

  35. Demo • 報告內容 • Project1 安裝過程介紹 • Project2 執行結果證明 • Project3 主程式介紹、執行結果證明 • 未完成項目和遭遇困難說明 • 把寫好的source code與報告(word檔)壓縮成 ”學號.tar.gz”，email to: kkw@networklab.csie.ncu.edu.tw

  36. Demo (cont.) • 郵件主旨請定為 • NachOS project #NO.，學號：姓名 • Ex: NachOS project #1，965402001:周立德 • 助教收到 email 後會回信表示收到 • 如果一週內沒收到回信，請再寄一次

  37. Something you need to know • Don’t modify the files under “machine” directory. • Please keep a copy of your code in your own PC. Course machine is for coding and testing. We don’t guarantee the safety of your codes.

  38. References • http://www.cs.washington.edu/homes/tom/nachos/ • http://inst.eecs.berkeley.edu/~cs162/sp08/Nachos/ (JAVA NachOS) • http://www.student.cs.uwaterloo.ca/~cs350/common/install.html Installation: • http://flyingwinnie.blogspot.com/2008/05/nachos.html redhat 9.0 • http://www.youtube.com/watch?v=epT7eFJLxls ubuntu 11.04 • http://www.student.cs.uwaterloo.ca/~cs350/common/install.html ubuntu 10.10 • http://www.youtube.com/watch?v=plGyUq4PcVA ubuntu 10.10

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