9 Questions
¿Qué significa FCFS?
First-Come, First-Served
¿Qué algoritmo de programación de procesos prioriza los procesos con el tiempo de ráfaga más corto?
SJF
¿Cuál es la fórmula para calcular el tiempo de espera promedio para un proceso?
(tiempo de finalización - tiempo de llegada - tiempo de ráfaga
¿Cuál es la técnica utilizada para calcular el tiempo de ráfaga predicho para un proceso?
Técnica de promediación exponencial
¿Qué parámetro determina el peso que se le da a los datos históricos versus los datos actuales en la técnica de promediación exponencial?
Alpha (𝛼
¿Qué enfoque se puede utilizar para asignar porciones de tiempo a cada cola de procesos?
Técnica de asignación de tiempos
¿Qué algoritmo agrega flexibilidad al permitir que los procesos cambien dinámicamente de cola?
Feedback queueing algorithm
¿Por qué es importante la priorización de procesos en diferentes colas en la programación de procesos?
Para prevenir la inanición de procesos de baja prioridad
¿Qué técnica previene la inanición de procesos de baja prioridad?
Técnica de envejecimiento
Study Notes
- The text discusses two scheduling algorithms: FCFS and SJF.
- FCFS stands for First-Come, First-Served, while SJF stands for Shortest Job First.
- SJF prioritizes processes with the shortest burst time.
- The formula for calculating the average waiting time for a process is (completion time - arrival time - burst time).
- The formula for calculating the average waiting time for all processes is the sum of individual waiting times divided by the number of processes.
- The exponential averaging technique is used to calculate the predicted burst time for a process.
- The parameter alpha (𝛼) determines the weight given to the historical data versus the current data.
- A value of 𝛼 = 0 ignores the current data, while a value of 𝛼 = 1 ignores the historical data.
- A value of 𝛼 = 0.5 is commonly used to balance both historical and current data.
- An example is provided to demonstrate how FCFS and SJF algorithms can be used to calculate the average waiting time for a set of processes.
- Prioritization of processes in different queues is important in process scheduling.
- Queue 1 has higher priority than Queue 2, meaning processes in Queue 2 cannot execute while processes in Queue 1 exist.
- The same applies to Queue 3, which cannot execute while processes exist in Queues 1 or 2.
- Another approach is to assign time slices to each queue, allowing them to access a certain percentage of the CPU.
- For example, 60ms can be assigned to Queue 1, 30ms to Queue 2, and 10ms to Queue 3.
- This allows each queue to manage its processes with its preferred algorithm within its assigned time slice.
- The feedback queueing algorithm adds flexibility by allowing processes to dynamically change queues.
- This allows a process to move to a higher or lower priority queue based on its current status.
- The feedback queueing algorithm can improve system performance by reducing process waiting times.
- Process scheduling is an essential aspect of operating systems.
- Processes need adaptive resource allocation
- High CPU usage processes can be moved to lower priority queues
- Aging technique prevents starvation of low priority processes
- Figure 5 extends the example from Figure 4 with feedback queues
- Queue 1 has absolute priority over Queue 2 and 3
- New processes enter Queue 1
- Processes with bursts under 5ms return to the end of Queue 1
- Processes with bursts over 5ms move to the end of Queue 2
- Processes in Queue 3 can access the CPU only when Queues 1 and 2 are empty
- Parameters for implementation include number of queues, scheduling algorithm, promotion and degradation methods, and assignment method.
Test your knowledge of process scheduling algorithms with this quiz! Learn about First-Come, First-Served (FCFS) and Shortest Job First (SJF) algorithms, how to calculate waiting times for processes, and the importance of prioritizing processes in different queues. Discover the benefits of the feedback queueing algorithm and how it can improve system performance. Challenge yourself to answer questions on adaptive resource allocation, aging techniques, and the parameters for implementing process scheduling. Sharpen your understanding of operating systems with
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