ICS 53留学生程序写作、辅导Java

” ICS 53留学生程序写作、辅导JavaICS 53, Winter 2021Assignment 3: Virtual Memory SimulatorYou will implement a VM Simulator which will simulate the operation of a virtual memory system.To launch the system, your simulator will accept one optional command-line argument for theselection of the page replacement algorithm. The system will then accept commands to read/writefrom/to a virtual address space. Your system will need to correctly move pages between disk andmain memory in order to satisfy access requests. Your system will need to properly maintain thepage table as part of this process.3.1 Parameters of the Virtual Memory SystemEach address in memory stores a single integer. All memory locations are initialized to the value of-1. All virtual pages are initially on disk, so the valid bits of all page table entries are equal to 0.Your virtual memory system Will have 64 addresses (0 – 63) and main memory has 32 addresses (0 -31). Each page contains 8 Addresses, so your virtual memory system will have 8 pages and your mainmemory will have 4 pages. Pages are numbered sequentially starting at the lowest memory address.So page 0 contains addresses 0-7, page 1 contains addresses 8-15, and so on. And the disk pagenumber of each virtual page is the same as the virtual page number.3.2 User Interface of VM SimulatorThe user will type in a sequence of commands and your program will perform the operation specifiedby each command. Your program will execute in a loop which starts with your program printing a prompt at the beginning of the line in order to let the user know that your program is ready toreceive a new command. The user will type in a command, followed by any necessary arguments,and then hit the enter key to indicate that the command is complete. Your program will thenexecute the command, print data to the screen if necessary, print a prompt on a new line toreceive a new command. (Note: is one and one space.)3 CommandsYour program must (and will only) process the following user commands.1. read virtual_addr: This command prints the contents of a memory address. The commandtakes one argument Which is the virtual address of the memory location to be read. When a page faultoccurs, A Page Fault Has Occurred\n is printed to the screen before the contents of a memoryaddress.2. write virtual_addr num: The command writes data to a memory location. The commandtakes two arguments, the virtual address to write the data to, and an integer which will be written tothe address. When a page fault occurs, A Page Fault Has Occurred\n is printed on the screen.3. showmain ppn: This command prints the contents of a physical page in the main memory. Thecommand takes one Argument which is the number of the physical page to be printed. Since eachpage contains eight addresses, eight contents of addresses should be printed and together with theirassociated physical addresses. You can see the format from the example below which shows thecontents of physical page 1 that includes the value 100 at address 8, the value 101 at address 9, thevalue 102 at address 10, and so on.8:1009:10110:10211:10312: 10513: 10714: 10115: 1004. showdisk dpn: This command prints the contents of a page on disk. The command takes oneargument which is the number of the disk page to be printed. Since each page contains eightaddresses, eight contents of addresses should be printed and together with their associated addresses.The format for printing the contents of the disk page is the same as the showmain command.5. showptable: This command prints the contents of the page table. Your virtual memory systemcontains 8 virtual pages, so this command will print 8 page table entries. Each page table entrycontains three fields of information about a page.● Valid bit: 1 indicates that the corresponding page is in main memory and 0 indicates that thepage is on disk.● Dirty bit: 1 indicates that the corresponding page has been written to while in main memory.0 indicates that the page has not been written to since it has been in main memory. The dirtybit has no meaning if the page is not in main memory, i.e. if the Valid bit is 0.● Page Number (PN): This is an integer indicating the number of the page (in main memory ordisk) where the virtual page can be found in memory. The PN refers to a main memoryphysical page when the Valid bit is equal to 1, and the PN refers to a disk page when thevalid bit is 0.The showptable command will print the contents of each page table entry on a separate line in thefollowing format, Where each line is divided by colons with four entries, virtual page number, Validbit, Dirty bit, and PN. Below is an example output of a page table from the showptable command.For instance, the first line represents that At virtual page number 0, Valid bit is 1 and Dirty bit is 0,and Page Number is 0.0:1:0:01:1:1:32:0:0:2…Although the above example only shows 3 pages for brevity, your showptable command shouldprint all 8 pages from the page table.6. quit: This command quits the program. (Note: No need to print anything.)3.4 Page Replacement Algorithm (Handling page faults)When a page fault occurs, a disk page must be copied into the main memory. If there is one or morepages in main memory which is available (there is not a virtual page mapped to it) then the disk pageshould be copied into the available main memory page with the lowest page number. If all pages inmain memory are in use, then a victim page must be chosen for eviction from main memory.You will implement two page replacement algorithms, FIFO and LRU, for the virtual memorysystem. And the page replacement algorithm will be selected at startup.- FIFO: The simplest algorithm is First-In-First-Out replacement. When a page fault occurs,the page that has been the longest in the main memory will be replaced.- LRU: The near-optimal algorithm is Least Recently Used replacement. When a page faultoccurs, the page that is the least recently used/accessed in the main memory will be replaced.show* commands do not count as use.Remember that the victim page must be copied back to disk before it is evicted if its own dirty bit is1. When a victim page is copied back to disk, always copy it back to the disk page whose number isthe same as the number of the virtual page.Your simulator Should accept EITHER FIFO or LRU as the command-line argument OR nocommand-line argument, which by default adopts the FIFO algorithm. The following examples showhow your simulator should launch the system. We assume that the linux prompt is the symbol $ and the executable is named a.out.$ ./a.out The system, by default, adopts the FIFO replacement algorithm.Additional Note:For the sake of simplicity, the page table will be assumed to be stored separately from the mainmemory. This means that when you issue the showmain command you will not see the page tablecontents. Also, when you issue the showptable command you will not see the main memory.For keeping counters please do not use time(NULL)because it will cause issues when running withautoCoverage.py. Use a global counter as a clock instead which increments by 1 each time you issueany command. Assume maximum number of commands will be 255.3.5 Testing instructions:For this assignment you will need to create a set of tests for your program which collectively achieve100% line coverage, executing every line of code in your program. You will need to submit your testdata so that we can verify that you have achieved 100% line coverage. We have created a Pythonscript called autocov.py which you should download with the assignment and use before you submityour assignment in order to ensure that you have achieved 100% line coverage. The autocov.py scriptwill compile and execute Your code with a set of test cases which you define and it will report theline coverage achieved by the test case. Do not modify the autocov.py script which we provide.Test RunsTesting is performed by executing your program a number of times with different test data. Each testexecution of your code is referred to as a test run (run for short) and the test data associated witheach run must be stored in a .run file. A .run file will contain all of the test data which will besupplied to your program during a single test execution. There are two types of test data which can besupplied to your program, command-line inputs and interactive inputs. Command-line inputs arethose supplied at the command line when the program is invoked, and interactive inputs are thosesupplied during the execution of the program through stdin, typically from the keyboard.A .run file is a text file describing all of the inputs supplied to your program for a single execution.The name of each .run file must have the suffix .run, but the prefix does not matter. Each line of a.run file can be no longer than 80 characters. The first line of the .run file is a series of command-linearguments passed to the program when it is invoked. Each command-line argument on the first lineof the .run file Must be separated by at least one space or tab character. The remaining lines of the$ ./a.out FIFO The system adopts the FIFO replacement algorithm.$ ./a.out LRU The system adopts the LRU replacement algorithm.run files contain a sequence of interactive inputs which will be supplied to your program throughstdin, as if they were typed into the keyboard.Input to autocov.pyThe autocov.py script requires your access to the source code of your program and the set of .runfiles to be used during testing. Your source code file must be named hw.c. This is important; it isthe only file which will be compiled by the script. Any number of .run files may be provided. All ofthese files, hw.c and all of your .run files, must be zipped together into a single zip file namedhw.zip. You can create the zip file using the zip command on linux. For example, if you havetwo .run files called t1.run and t2.run then you could create the zip file with the followingcommand: zip hw.zip hw.c t1.run t2.run. The hw.zip file is the only input to the autocov.py script.Running autocov.pyIn order to execute the script, the autocov.py file must be placed in the same directory as the hw.zipfile and another directory called hw. The hw directory will be used by the script to compile and runyour program, so it should be empty before running the script. The script needs to be run using aPython interpreter version 3.6.8 or later. On the openlab systems the command python3 invokesthe Python 3.x interpreter, so you can run the Autocov.py script by entering the command python3autocov.py. The script will Print a number of lines to the screen, including program outputs, but thesecond-to-last line should look like this, Lines executed: X% of Y, where X is the line coverageand Y is the number of lines in your program.3.6 Submission Instructions:Your source code and .run files must be submitted as a single .zip file. Your source code file must benamed hw.c. This is important; it is the Only file which will be compiled by the script. Any numberof .run files may be provided. All of these files, hw.c and all of your .run files, must be zippedtogether into a single zip file named hw.zip. You can create the zip file using the zip commandon linux. For example, if you have two .run files called t1.run and t2.run then you could createthe zip file with the following command: zip hw.zip hw.c t1.run t2.run. Be sure that your programcompiles on openlab.ics.uci.edu using gcc version 4.8.5. Also, be sure that no compiler switches areused, other than -o and the switches required for gcov.Submissions will be Done through Gradescope. You can follow this video to create a groupassignment on Gradescope. The first line of your submitted file should be a comment which includesthe name and ID number of you and your partner (if you are working with a partner).3.7 Example UsageFollowing the above assumption, this is an example, launching the system with the FIFOreplacement Algorithm. The text typed by the user is bold.$ ./a.out FIFO showptable0:0:0:01:0:0:12:0:0:23:0:0:34:0:0:45:0:0:56:0:0:67:0:0:7 read 9A Page Fault Has Occurred-1 write 9 201 read 9201 showmain 00:-11:2012:-13:-14:-15:-16:-17:-1 showptable0:0:0:01:1:1:02:0:0:23:0:0:34:0:0:45:0:0:56:0:0:67:0:0:7 quit$ you are back to the linux prompt.Additional Example Usage (eviction from main memory)This is Another example, launching the system with the LRU replacement algorithm. The text typedby the user is bold.$ ./a.out LRU write 10 202A Page Fault Has Occurred write 31 403A Page Fault Has Occurred read 19A Page Fault Has Occurred-1 read 0A Page Fault Has Occurred-1 read 12-1 Write 9 300 showmain 18:-19:-110:-111:-112:-113:-114:-115:403 showdisk 324:-125:-126:-127:-128:-129:-130:-131:-1 Showptable0:1:0:31:1:1:02:1:0:23:1:1:14:0:0:45:0:0:56:0:0:67:0:0:7 read 32A Page Fault Has Occurred-1 showmain 18:-19:-110:-111:-112:-113:-114:-115:-1 showdisk 324:-125:-126:-127:-128:-129:-130:-131:403 showptable0:1:0:31:1:1:02:1:0:23:0:0:34:1:0:15:0:0:56:0:0:67:0:0:7 quit$ you are Back to the linux prompt.如有需要，请加QQ：99515681 或WX：codehelp

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