SCHEDULING PROCESS - Operating Systems

SCHEDULING PROCESS
• A set of policies and mechanisms on the Operating System with respect to the order of the work done    Computer Systems.
• In charge of deciding who should run the process, when and for how long the process runs.
• Goal à ..!!! PERFORMANCE OPTIMIZATION

CRITERIA SCHEDULING PROCESS

1. FAIR (Fairness)
      Fair is where the processes are treated the same which gets a small processor and the same time there is no process that gets no processing services.
      Target scheduling is to ensure every process gets a fair part of the processing.

 

2. EFFICIENCY (CPU Utilization)

      Scheduling keep the unused processor continuously as long as there is an active process in the queue ready, generally proses2 waiting user input or I / O operations will be blocked and Blocked status, so that did not participate in the scheduling process.

      Target processor scheduling is to keep busy in order to remain in a state so that maximum efficiency. Busy refers to the processor is not idle, including the time spent to execute user programs and SO.

3. RESPONSE TIME (Response Time) Response time in interactive systems is the duration of time between the user provides input to the operating system to provide output or feedback to users, Target scheduling is to minimize response time.

4. WAITING TIME (Waiting Time) Represents a duration of time spent in the queue ready prses during their life cycle. In general, a good scheduling algorithm produces an average waiting time is small for the entire process .

5. ARROUND TURN TIME (TA) Turn Arround Time is the time spent from when the program or job started to get into the system until the process is completed the system. Represents the sum of the duration of the execution process (running) with a duration of waiting (waiting).

Turn Arround Time:
Old Execution + Waiting Time
or
Done Execution - Time Arrives  

6. Throughput

    Throughput is the average process can be completed per unit time

The way to express the throughput is the number of user jobs that can be executed in one unit / time interval.

     schedule goal is to maximize the number of jobs that are processed at a time interval. Higher throughput rate, the more work done by the system.

Throughput: S TA / S process