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We have two exercises in this experiment. 1. In this exercise, we will conduct the following steps to understand race condition problem in Nachos. 1) Change your working directory to lab2 by typing cd ~/nachos-3.4/lab2 2) Read the Nachos thread test program threadtest.cc carefully. There is a shared variable named value (initially zero). There are two functions, namely void Inc(_int which) and void Dec(_int which), where increases and decreases value by one, respectively. In this exercise, you need to consider different interleaving executions of Inc and Dec so that the shared variable value is equal to a predefined value after threads complete. 3) You need to implement the following three functions. When all the threads (two Inc_v1 threads and two Dec_v1 threads) complete in TestValueOne(), value=1. void Inc_v1(_int which) void Dec_v1(_int which) void TestValueOne() In Inc_v1 and Dec_v1, you need to use Yield primitive in Nachos to induce context switch. Inc_v1 and Dec_v1 should have the same logic as Inc and Dec, respectively. You are only allowed to add Yield into those two functions. You need to implement ThreadValueOne() by creating two threads with Inc_v1 and two threads with Dec_v1. The current thread should wait for all those threads to complete. At the end of TestValueOne(), a checking is performed on whether the value is 1. If the checking is passed, you should get the message "congratulations! passed.". Otherwise, an error message is printed. 4) After you finish implementing the above-mentioned functions, you can demonstrate the result of TestValueOne(), by commenting other test functions in ThreadTest() like below. //for exercise 1. TestValueOne(); //TestValueMinusOne(); //for exercise 2. //TestConsistency(); 5) Compile Nachos by typing make. If you see "ln -sf arch/intel-i386-linux/bin/nachos nachos” at the end of the compiling output, your compilation is successful. If you encounter any anomalies, type make clean to remove all object and executable files and then type make again for a clean compilation. 6) Test this program by typing ./nachos. If you see “congratulations! passed.” at the end of the debugging messages, your program is successful. Otherwise, “failed.” will be displayed. 7) Repeat Steps 3)—6), and implement the following three functions. When all the threads (two Inc_v2 threads and two Dec_v2 threads) complete in TestValueMinusOne(), value=-1. At Step 4), you need to test TestValueMinusOne(). void Inc_v2(_int which) void Dec_v2(_int which) void TestValueMinusOne() 2. In this exercise, we will conduct the following steps to understand process synchronization problem in Nachos. 1) Change your working directory to lab2 by typing cd ~/nachos-3.4/lab2 2) You need to implement the following three functions. When all the four threads (two Inc_Consistent threads and two Dec_Consistent threads) complete in TestConsistency(), value=0. You need to achieve consistent result (value=0), regardless of different interleaving execution orders in Inc_Consistent and Dec_Consistent as well as different thread fork orders in TestConsistency(). void Inc_Consistent (_int which) void Dec_Consistent (_int which) void TestConsistency () In Inc_Consistent and Dec_Consistent, you use Yield interface in Nachos to induce context switch. You need to implement TestConsistency() by creating two threads with Inc_Consistent and two threads with Dec_Consistent. The current thread should wait for all those threads to complete. At the end of TestConsistency(), a checking is performed on whether the value is 0. If the checking is passed, you should get the message "congratulations! passed.". Otherwise, an error message is printed.3) After you finish implementing the above-mentioned functions, you can demonstrate the result of TestConsistency(), by commenting other test functions in ThreadTest() like below. //for exercise 1. //TestValueOne(); //TestValueMinusOne(); //for exercise 2. TestConsistency(); 4) Compile Nachos by typing make. If you see "ln -sf arch/intel-i386-linux/bin/nachos nachos” at the end of the compiling output, your compilation is successful. If you encounter any anomalies, type make clean to remove all object and executable files and then type make again for a clean compilation. 5) Test this program by typing ./nachos. If you see “congratulations! passed.” at the end of the debugging messages, your program is successful. Otherwise, “failed.” will be displayed. In the oral exam, you need to demonstrate your testing with different interleaving execution orders in Inc_Consistent and Dec_Consistent as well as different thread fork orders in TestConsistency().