Operating System NachOS Project
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Transcript of Operating System NachOS Project
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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: [email protected]
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Outline
What is NachOS How does NachOS work
– Source Tree– System Starting
Install NachOS Projects
– Installation– Multiprogramming– Scheduling
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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/
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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
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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
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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
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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
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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
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How does NachOS work
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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
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How does NachOS work
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How does NachOS work
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How does NachOS work
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Root directory
C++ introduction to teach how to write C++
Root directory of Nachos’s source code
File system
Nachos’s library
MIPS machine
In/Out message queues
NachOS’s sample user programs
threads
Source code of NachOS kernel and MIPS simulator
The tool to convert user programs from MIPS’s COFF into NachOS’s NOFF (NachOS Object File Format ) format
User programs’ interfaces: system calls, address space, noff format
Source Tree
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System Starting
code/threads/main.cc main
> ./nachos start
create kernel object
initialize the system
Start up interrupt handling
initialize the ready queue and scheduler
initialize MIPS machine
Run some system testingInvoke user program
Load user program
Run user program
System halt and terminate
No user program
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Install NachOS
Platform: Linux or Linux over VMware– RedHat Linux 9.0
Install steps– Get NachOS-4.0
# wget http://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
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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…
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The test1 result
Total threads number is 1Thread ../test/test1 is executing.Print integer:9Print integer:8Print integer:7Print integer:6return value:0No threads ready or runnable, and no pending interrupts.Assuming the program completed.Machine halting! Ticks: total 200, idle 66, system 40, user 94Disk I/O: reads 0, writes 0Console I/O: reads 0, writes 0Paging: faults 0Network I/O: packets received 0, sent 0
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The test2 result
Total threads number is 1Thread ../test/test2 is executing.Print integer:20Print integer:21Print integer:22Print integer:23Print integer:24Print integer:25return value:0No threads ready or runnable, and no pending interrupts.Assuming the program completed.Machine halting!
Ticks: total 200, idle 32, system 40, user 128Disk I/O: reads 0, writes 0
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Operate NachOS
NachOS command help– ./nachos -h
Debugging mode– ./nachos -s
Execute files on NachOS– ./nachos -e ../test/test1
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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
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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)
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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
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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
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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 2Thread ../test/test1 is executing.Thread ../test/test2 is executing.Print integer:9Print integer:8Print integer:7Print integer:20Print integer:21Print integer:22
Race Condition
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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
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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
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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)
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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。
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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
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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
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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?
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SJF Scheduling (cont.)
Begin Running
Invoke Sleep(x)
Per timer interrupt:1.Record actual CPU burst2. 叫醒應該起床的 threads
1.Set next predicted CPU burst2.Insert this thread to Sleeping thread lists3.Invoke thread->Sleep
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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: [email protected]
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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
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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.
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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