Idle (CPU)

The so-called idle process ( engl. idle task ) is a "pseudo " process, which always gets processor time in many operating systems, if no other process is running. This may be the case if no processes are ready to run, because they are waiting for example, I / O operations. In this way, the process scheduler can be simplified, since this case does not need to be treated separately, but simply the idle process is scheduled.

Nowadays instructions are with the change in the idle process usually associated, which put the CPU into a low power mode or clocked down, such as the HLT command (short for "halt" ) on x86 processors.

In the Windows operating system idle process in Task Manager in the tab is the "Processes" always displayed and often claimed seemingly much processor power. These are the unused processing time, that is the capacity, which is not claimed by applications. The sum of the proportions of all running processes on the processor utilization (including the idle process ) so is always 100 %. In the tab "Performance" but only the used by other processes, CPU performance is displayed, the " utilization " by the idle process in this case does not flow into the count.

On Unix-like operating systems, the command line program is top usually installed, the ( so for idle task ) outputs in the third row one with id highlighted value for the percentage of idle process on the overall utilization of all processors in the system.