OS Scheduling Algo Doubt

Replies

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  The_Small_k

  I don't think it's the scheduler to distinguish between IO bound job and CPU bound job.Generally these two jobs are mixed together to make the system balanced not because scheduler distinguish between them.
  Well i think these two jobs are distinguish by CPU brust.
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  Sachin Jain

  See there are two types of schedulers.
  Long Term Scheduler (which i am talking about) decides which job should be pushed into ready queue from new state.
  This selection decides the proper mix of IO bound jobs and CPU bound jobs in ready queue.
  Short Term scheduler decides which job should be sent from ready queue to active state i.e for execution.
  So i want to ask how this Long term scheduler decides which is IO bound job and which is CPU bound job.
  without even executing them.
  Tell me if my question is not clear.
• 

  The_Small_k

  If i understand your question correctly you want to know how a LTS decides that which one is IO bound and which one is CPU bound right ?
  Look a scheduler never decides the type of jobs.A scheduler job is to select the no of processes from the process queue.
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  Sachin Jain

  You are right man!
  But the thing you are saying is the job of Short term Scheduler.
  there are two types of scheduler
  Long Term Scheduler and Short term scheduler.
  STS decides which job should be sent from ready to active state (ofcourse you are right)
  I am talking about LTS not about STS....
• 

  The_Small_k

  Long term scheduler job is to select the processes which process should be placed in main memory.
  It will take all the processes that can be put in main memory(a necessary condition is the balanced equation).As i said earlier that CPU brust decides that which one among IO bound and CPU bound will get selected.
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  Sachin Jain

  Okk got it....Thanks..😀
• 

  The_Small_k

  Welcome Welcome...
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  Sachin Jain

  Hey small_k
  Sorry but i got some doubt.
  How does LTS come to know about the CPU burst of jobs because they have not been even executed yet.
  They are still in new state.
• 

  The_Small_k

  @blunderboy you are right that no process is done during the selection then how the LTS come to know about the cpu brust of jobs.
  Nice question !!
  I don't have any answer,i read somewhere that CPU brust is used to decide IO bound jobs and CPU bound jobs.
  Hope any CEan's can answer it !!