The Definition Of Idle In Windows

When is a computer idle? A friend of mine asked me that question the other day after playing around with the Windows Task Scheduler for a while. One of the conditions in the Task Scheduler is the on idle condition which executes the given task if the computer has been idle for a given amount of time.

But what exactly does it mean, idle? I had troubles answering that question. I knew that it had to do with the resource utilization and user interaction, but was not able to provide exact figures.

That sparked my interest and I managed to get the data. Here is the definition of idle in the Windows operating system:

The computer is considered to be idle by Windows if there has not been user interaction via the mouse or keyboard for a given time and if the hard drives and processors have been idle more than 90% of that time.

The Task Scheduler in Windows 7 for instance considers the computer to be idle if the above states returned true for a period of ten minutes.

There are a few exceptions to that rule. Applications may set a flag that prevents the computer from idle mode. Another possibility are low priority processes that may be ignored by the Windows 7 Task Scheduler. But that appears to be a Windows 7 only rule.

To paraphrase; The computer enters idle mode if

• users have not interacted with it for a period of ten minutes
• and if in the same time period the processor and hard drive utilization has been idle as well for at least 90% of the time