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Resources and Critical Section

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A task that is currently holding a unsharable resource is said to be in critical section associated with that resource.
  • Locking the resource mainly achieved by means of Binary Semaphores.
  • When a task wants to enter a critical section, it first checks whether the corresponding semaphore is taken or not. If the semaphore is locked,then the task will wait until the semaphore is unlocked.
  • Critical Sections are always properly nested Lock R1; Lock R2; Unlock R2; unlock R1.Where R1 and R2 are two resources.
Sharing a resource always leads to Priority Inversion Problem, that a high priority task is waiting to run under a CPU, whereas the low priority tasks are running locking a resource.
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