Why do my processes only consume 5% of the processors power?

Question

Not sure if this is the appropriate place for this question, but it seems related to threading and system resources and all that.

Why Does my Task Manager show that the System Idle Process is using 90%+ of the CPU power when I have 3 different processes going!?!?

Is it because of I/O bottlenecks?

For example, if I do an SVN checkout, and empty my recycle bin, and browse the web at the same time, why is the System Idle process at 97%, and the other processes around 1% each? None of them seem to actually be going very fast.

Answer 1

It really depends on what your processes are doing. If they are IO bound, then there's a good chance that they're sitting and waiting most of the time.

If they're winforms apps that wait for user input, then they sit there, doing nothing, and waiting for input.

Answer 2

Mostly the processes are waiting for disk or network operations to complete, or waiting for user input.

You might think you have a fast disk or network connection, but compared to memory/cpu it's like walking to the nearest library, looking up a book in the catalog and finding it on the shelf vs already having the book in your hand.

This is why you pay thousands or dollars for 10,000 and 15,000 rpm scsi drives (or even more for SANs) on high performance servers.

Answer 3

I can't say for sure. But I'd say I/O bottlenecks would be a large part of it. In fact, I wouldn't imagine any of the tasks you described would be very CPU intensive.

Now, try to re-encode a raw AVI file into DIVX format while simultaneously rendering a 3D animation in Maya, and your CPU should be plenty busy.

Answer 4

SVN checkout and recycle bin emptying are both very heavy disk activities with not much demand on the CPU, and web browsing is very spiked in terms of CPU usage (spikes when rendering pages, for example, but costs very little once that is done).

If you want to see your CPU sustain high utilization, do something that is almost purely CPU/memory based, like Folding@Home.