Comments for What is the System Idle Process and why is it using most of the CPU?

Comment from Andrew Milton on 2008-08-26

2008-08-26T10:03:25Z

The point seems to be that users expectations are that the SIP should not take over the machine, but it does, interferring with the usefulness of the computer. There have been many times for me when a program has appeared to have crashed when in fact the computer is just busy doing the SIP. If the SIP is housekeeping processes and commands to keep the processor occupied during periods when programs are inactive then as soon as a program requires the CPU, the SIP should be suspended. So either the SIP has been badly programmed or it is more than the computer sorting itself out. Either way this is very frustrating to users and a way to control the SIP would be really welcome.

By definition, the system idle process does nothing. That's why it's called "idle". It doesn't "take over" your machine ... if your machine is in an idle state that means it's doing nothing and ready to do something else.

-Leo

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Comment from Greg Webb on 2008-03-23

2008-03-23T22:56:28Z

Sometimes my machine is running idle and it cannot be interrupted. That is, the idle process is too busy to notice keystrokes and mouse clicks.

Leo, do you know why this is happening?

I once read something about WinXp automatically moving files about, a kind of optimisation. When I can't interrupt the idle process there is certainly a lot of disk processing (I can hear the heads thrashing). I haven't been able to find the information about automatic file positioning again and sometimes wondering if it was a figment of my imagination.

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A comment on: What is the System Idle Process and why is it using most of the CPU?

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Comment from Octav on 2008-03-22

2008-03-23T02:37:32Z

Simon said: "which raises the question of what the CPU would be doing that would use power if the OS *didn't* continually issue these HLT commands."

Adding 0 to 0. Repeatedly. :)

Actually, that's a joke. What it would do is check over and over again if anything's happening, like a key being pressed or the like. Read http://en.wikipedia.org/wiki/Busy_waiting (and http://en.wikipedia.org/wiki/HLT while you're at it).

Also, thanks for pushing me to research this :)

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A comment on: What is the System Idle Process and why is it using most of the CPU?

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Comment from David Hawkins on 2008-03-22

2008-03-22T10:41:02Z

Hi
The Idle Process can kick in when you are engaged in when you are using Movie Making software and are downloading or writing video causing you to lose or get distorted clips or frames. To get around this you can deliberately start the Idle Process so that it effectively gets it out of the way and won't start up in the middle of your movie making. You can also use a little program called "End It All" which also helps, but thats a different thread.
David

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Comment from David Ball on 2008-03-18

2008-03-18T15:38:19Z

On Vista machine you'll also find that "SearchIndexer.exe" may be chewing up lots of CPU time from time to time. Vista will only show the current user's processes initially - if the user is logged in as an administrator, they can click on the Show All Processes button on the bottom of the dialog box to see everything running on the system.

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Comment from Mike Carretti on 2008-03-17

2008-03-18T03:24:43Z

I am using WIN Vista Home Premium. I ran Task Manager, went to Processes, sorted the list and could not find the System Idle Process. Whats up with that?

Thanks

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Comment from Simon on 2008-03-17

2008-03-18T02:23:31Z

Apparently, what the System Idle Process is actully doing is continually issuing HLT commands to the CPU; HLT being a command which, according to http://download.intel.com/design/PentiumII/manuals/24319102.PDF, "stops instruction execution and places the processor in a HALT state ... An enabled interrupt, NMI, or a reset will resume execution".

Apparently doing this saves power, which raises the question of what the CPU would be doing that would use power if the OS *didn't* continually issue these HLT commands. Any ideas?

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Comment from Greg Bulmash on 2008-03-17

2008-03-17T18:33:44Z

The devil finds work for idle processes. :-)

And so does BOINC.

http://boinc.berkeley.edu/projects.php is a list of projects you can donate idle cycles to when you install the BOINC software. It can either run in the background as a low-priority process, eating up idle cycles, but giving up cycles when your priority programs need them, or as a screensaver, using more of your CPU when the whole system is idle.

The projects range from evaluating radio signals from space for signs of E.T. communication to helping with complex mathematical modeling. It's a great way to take those idle cycles away from the System Idle Process and donate them to worthwhile projects, making your computer a voluntary node in a giant distributed supercomputer.

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A comment on: What is the System Idle Process and why is it using most of the CPU?

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