High CPU load from System when idle

I run Windows 8 Pro 64bit on a ~3 year old Sony Vaio.

Pretty much since I installed Windows 8 I get high CPU load when I leave the system alone for a couple of minutes.

The high load will continue (usually one core fully utilized) until there is some user input. In the beginning this was the defrag process, but after fixing that, I am getting high CPU load from the System process.

I have run Windows Performance Recorder - the idle activity sets in about 4 minutes after the last input, the biggest culprit seems to be a function called RtlScrubMemory in the NT kernel: WPA (show large pic)

The system has 8GB RAM, Task Manager shows about 3.5 GB memory use, so memory shortage should not be an issue.

Googling did not really turn up anything useful - any help would be appreciated.

Edit: Here is the ETL file: link

Martin

Posted 2013-08-23T16:43:11.543

Reputation: 665

What's up with the downvote? Any reason? – Martin – 2013-08-23T17:24:20.047

See this question. A Sony Vaio running Vista where the problem was apparently related to a glitch in the WiFi radio logic such that I got 100% on one CPU when the radio was turned off. Installing Windows Process Explorer (free from MS for Vista, at least) made it possible to zero in on the interrupt system, leading to the suspicion that it's an "open" interrupt line causing repeated hardware interrupts, likely due to a WiFi driver glitch.

– Daniel R Hicks – 2013-08-23T18:15:05.550

use this command which also traces VirtualAlloc/VirtualFree: http://pastebin.com/4h2ySm1V Maybe this shwos which other tools allocate memory.

– magicandre1981 – 2013-08-23T21:21:34.540

Answers

ok, because I saw the RtlScrubMemory issue several time I asked Microsoft about it. This functions is used to test the installed RAM.

I saw it when the idle Maintenance kicks up and tries to optimize Windows. Disable the Idle Maintenance task in task scheduler to get rid of it.

magicandre1981

Posted 2013-08-23T16:43:11.543

Reputation: 86 560

That seems to help, actually. Did you get any info on what triggers this memory scrubbing spree? Is this is a problem caused by bad RAM? – Martin – 2014-06-06T16:40:55.593

I haven't got any details about this function from my Microsoft contact. – magicandre1981 – 2014-06-07T05:47:30.913

Could be a driver issue (in my experience, when Windows is acting strange, a driver is almost always at fault), you could try binary searching the extraneous drivers and seeing if disabling any of them causes the problem to go away (disable all non-necessary drivers, reboot. If problem goes away, re-enable half of them and see if it returns. Wash, rinse, repeat).

My suspicion would be a network driver, so those are the ones that I'd start with.

Also worth noting that the ETL trace shows fairly high usage from a svchost, which could be what's calling the scrubmemory.

Ross Aiken

Posted 2013-08-23T16:43:11.543

Reputation: 372

the svchost.exe usage comes from Defrag service. but this is fine. – magicandre1981 – 2013-08-23T21:16:37.977