What's a CPU to do when it has nothing to do?

Re:What's a CPU to do when it has nothing to do? by bonzini on Thursday October 11, 2018 @04:25AM (#18191773)

IDLE is the priority of a process that runs only when the system is otherwise idle. It shouldn't be preempted by zeroing memory.

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by na412 on Thursday October 11, 2018 @05:10AM (#18191962)

But then under what circumstances will the zero page thread ever be scheduled?

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by masklinn on Thursday October 11, 2018 @09:53AM (#18193520)

It's confusing, but "idle" is a priority class as well as a state: https://docs.microsoft.com/en-us/windows/desktop/procthread/...

The idle task (when there's nothing to run) doesn't have a priority at all, it just gets run when nothing else is available. the "idle" priority is an actual priority, for when there's no higher-priority task to run. The ZPT is prioritized below "idle", so super-duper-low priority.

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by dTal on Friday October 12, 2018 @05:09AM (#18200214)

Thank you for this clear explanation. It is confusing!

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by blattimwind on Thursday October 11, 2018 @07:07AM (#18192444)

When there are no runnable idle threads.

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by chaosite on Thursday October 11, 2018 @05:14AM (#18191969)

So the zero page process runs when one core is busy but the rest are free?

[ Parent | on HN ]

Re:What's a CPU to do when it has nothing to do? by klodolph on Thursday October 11, 2018 @09:29AM (#18193337)

It runs when the there are no higher-priority processes to schedule on a particular core. IDLE processes are higher priority, so as long as an IDLE process can be scheduled, the zero page process won't run.

[ Parent | on HN ]