System Idle Process???

Does anyone know what the "System Idle Process" is, or does, or why it would be using 99% of the CPU?

Skriker V1.0 wrote:

Does anyone know what the "System Idle Process" is, or does, or why it would be using 99% of the CPU?

Its just a "process" (I'm not sure if it actually exists as a traditional process, per se) that exists to count up how long the CPU's been idle.

You'll notice the "99%" CPU that the taskmanager reports isn't actually 99% of the CPU's resources, but 99% of the unused resources. Don't ask.

It's not "doing" anything. It represents the the % of CPU not doing anything for other processes.

Cheers

Anyone know where to get a list of what all the common windows processes are and what they do?

Just type the process name into Google, that usually works.

W3bbo wrote:

You'll notice the "99%" CPU that the taskmanager reports isn't actually 99% of the CPU's resources, but 99% of the unused resources.

Fixed

The percentage indicates the part of the time the cpu is spending running that process, obvioulsy the sum of all values should give 100.
Well, that 99% is the time the processor is spending running null operations (idle) in that moment.
The cpu clock is almost constant, there is no time while the processor is running slower, it's always running 100%, doing some work or some null operation.

NeoTOM wrote:

W3bbo wrote:You'll notice the "99%" CPU that the taskmanager reports isn't actually 99% of the CPU's resources, but 99% of the unused resources.

Fixed

Ah, thanks

eddwo wrote:

"REBOOT DISABLED. Starting some months ago, hitting Ctrl-Alt-Delete twice would no longer reboot my system. Now I get a dialog box and have to reboot from inside that or not at all."

Yes, some months ago when he installed any version of NT rather than Windows <=3.1.

Windows 98 still had the Ctrl-Alt-Delete-twice-to-reboot behavior.  I'm guessing Windows ME does as well.

But his article was written in 2003, so he has no excuse.

Well the modern low power CPUs, the Yonah and Dothan etc, all dynamically change speeds as requirements demand.

Also an idle CPU will regularly enter a sleep state when no operations are performed and parts of the chip shut down. All modern systems routinely support this feature by executing the HLT instruction.
 A timeout or hardware interrupt will instantly wake the CPU and start it running again.

The system idle process is responsible for zeroing out unused pages of memory, but its basic purpose is to account for all the unused cycles.

John Dvorak also can't seem to understand the concept.

"When I hit Ctrl-Alt-Delete, I see that the System Idle Process is hogging all the resources and chewing up 95 percent of the processor's cycles. Doing what?"

The next bits quite funny too.
"REBOOT DISABLED. Starting some months ago, hitting Ctrl-Alt-Delete twice would no longer reboot my system. Now I get a dialog box and have to reboot from inside that or not at all."

Yes, some months ago when he installed any version of NT rather than Windows <=3.1.

I wasn't sure it was an automatic reboot. Its ages since I've used 98, but I thought it gave an bluescreen message first and let you resume if you wanted.

His article is about how his install of XP had slowed after installing lots of patches. I guess he had never noticed before that it had never rebooted itself on Ctrl-Alt-Del

I thought Double-CAD presses were captured by the hardware, rather than the OS, so a "hard reboot" would have happened anyway.

Found this http://www.tasklist.org/ 

W3bbo wrote:

I thought Double-CAD presses were captured by the hardware, rather than the OS, so a "hard reboot" would have happened anyway.

No hardware is involved.  Ctrl-Alt-Del is not a hard reboot.  Exactly how far along the boot process Ctrl-Alt-Del takes you depends on the partical BIOS and it's Ctrl-Alt-Del handler.

Ctrl-Alt-Del is simply a "magic" keystroke that the BIOS would recognize, and trigger a soft reboot.  This was in the early PC BIOSes, and has been carried forware in the name of backwards compatiblity.

On modern operating systems which don't use the BIOS (Windows NT/2000/XP, Linux), they are free to hook Ctrl-Alt-Del however they want.

The fact that these OSes use Ctrl-Alt-Del to trigger a "special" event is simply a historical convention.  They don't need to follow what the BIOS does.  Under Windows, it could just as easily be Ctrl-Alt-Z, or something else.