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Project 3 Roadmap

Project 3 Roadmap. Multilevel Feedback Scheduling Semaphores. Multilevel Feedback Scheduling. struct Kernel_Thread in kthread.h current queue: int currentReadyQueue blocked state: bool blocked there are 4 run queues now: s_runQueue[MAX_QUEUE_LEVEL] in kthread.c

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Project 3 Roadmap

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  1. Project 3 Roadmap Multilevel Feedback Scheduling Semaphores

  2. Multilevel Feedback Scheduling • struct Kernel_Thread in kthread.h • current queue: int currentReadyQueue • blocked state: bool blocked • there are 4 run queues now: • s_runQueue[MAX_QUEUE_LEVEL] in kthread.c • a thread is initially in s_runQueue[0] • except IDLE thread that enters at 3 when switching to MLF mode • check the scenarios • Find_Best() automatically pick the highest priority thread in a queue • Get_Next_Runnable() will call Find_Best() for each queue until it finds a ready process

  3. Multilevel Feedback Scheduling • end of quantum ? • if blocked promote • if has just run demote (check TODO in Timer_Interrupt_Handler() defined in timer.c) • make sure your Sys_SetSchedulingPolicy() works before stuff gets complicated • A thread becomes blocked in Wait().

  4. Semaphores • rough guideline • add two files sem.h/sem.c • create a semaphore structure • each has a thread queue, count, name, etc • P/V semantics • P decrease, block if needed • V increase, never blocks • section 7.4.2 in the textbook, pp 203

  5. Testing Your Code • workload.exe [rr/mlf] [quantum] • ping.exe & pong.exe

  6. GetTimeOfDay() • Sys_GetTimeOfDay - trivial • (return g_numTicks)

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