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System Idle Process and it's Existence RRS feed

  • General discussion

  • First off, this is not related to any problem. This is simply a question I had when I was sitting in my office taking a break.

    Also, before I ask, I understand the purpose behind the System Idle Process. I understand what it does, specifically that it runs HLT and complex power-saving threads when no other work is being done.

    My question is, what would happen to the CPU if the System Idle Process did not exist? I understand a CPU can never truly be idle (in the since of no threads moving on it) so what would happen if it ever did find itself without any threads, including idle threads?

    Just a curiosity, nothing more...


    Owner, Quilnet Solutions

    Friday, February 15, 2013 4:45 AM

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    Friday, February 15, 2013 5:10 AM
    Moderator
  • You need to change your view of the System Idle process. It's like you asking your boss 100 times each day what you could do for him. If your boss gives you a job 80 times then you are idle for 20% of the time. It's the same with the CPU: When the System Idle process "runs" at 98% then the processor spends just 2% at housekeeping chores (such as power saving tasks) but "twiddles" its thumbs for 98% of the time.

    The only way to reduce idle time is to give the CPU something to do.

    And the only way to get rid of your own idle time is to get you to work 7 days a week, 24 hours a day . . .
    Friday, February 15, 2013 7:12 AM
  • Right, I know this already. My question is, from a hardware-POV, is there any danger to the CPU if there literally was no System Idle Process? Would it seize up or something?

    Owner, Quilnet Solutions

    Friday, February 15, 2013 2:07 PM
  • When the idle process shows almost to CPU time then the CPU is almost fully loaded (which you can see in the performance graph). Under those circumstances it won't "seize up" but it will heat up which you can notice because the fan will spin faster.

    Remember - a CPU continuously runs a fixed number of cycles every second as set by its clock frequency. It never ever stands still. You might want to read this article to get a better appreciation of it.

    Friday, February 15, 2013 2:44 PM
  • If the system idle process were to somehow terminate (which does not happen, but theoretically speaking), the system would most likely crash. There is a dynamic schedule that the CPU follows; it tells the CPU what thread to process in any given moment. If no thread needs or wants processing power, then the scheduler will put the system idle process on the schedule. If there is no system idle process then there will be no valid thread on the schedule, at which point the CPU will not know what it was supposed to do. It would probably stop functioning all together, instantly crashing the computer.
    Tuesday, October 16, 2018 2:17 AM