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Every once in a while (I can't pin down exactly when, but it seems to be correlated with when the computer is idle for a while), the System process on my Windows 8.1 x64 machine suddenly starts using 100% of Core 1 of my CPU (8-core, so 12.5% of total CPU time).
To fix it, I usually just reboot (the laptop fan noise is annoying) -- although I recently noticed it seems to automatically calm down after 5-10 mins of activity.

I've tried to find the culprit using Process Hacker, and it seems to be the function MmTrimAllSystemPagableMemory as shown in the image below.

I don't remember if this happened on Windows 8.0, but this has never happened to me before, when I've had Windows 7 or earlier. So I'm confused what has changed, because this is a pretty old function.

What might be causing this? Is there some way for me to prevent it?

For what it's worth, it seems this is related somehow to a Task (ResolutionHost?) and relevant APIs include MmScrubMemory and CMemoryDiagnosticHandler:

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    Why the downvote?
    – user541686
    Dec 20, 2013 at 3:25
  • do you use an older VMware version which is not 8.x compatible? Also provide a xperf trace: pastebin.com/pgE11HRD Dec 20, 2013 at 5:17
  • @magicandre1981: I don't use VMware at all. Thanks for the link, I'll try it the next time it happens (I'm not sure how to reproduce it myself).
    – user541686
    Dec 20, 2013 at 5:39
  • btw, use this command: pastebin.com/4h2ySm1V It also captures some memory data. Dec 20, 2013 at 18:23
  • @magicandre1981: It just happened again, but when I tried xperf I got xperf: error: NT Kernel Logger: Cannot create a file when that file already exists. (0xb7).
    – user541686
    Jan 2, 2014 at 20:50

1 Answer 1

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

Look if the idle Maintenance kicks up (look into the process graph) and tries to optimize Windows. if yes, disable the Idle Maintenance task in task scheduler to get rid of it.

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  • +1 thank you for posting this. How did you ask about it if you don't mind me asking -- online on some support page, or did you know an employee?
    – user541686
    Jun 7, 2014 at 7:40
  • I've asked this directly a MS employee Jun 7, 2014 at 16:23
  • Seems like this isn't the exact issue, because my SYSTEM process is currently utilizing an entire CPU but the Idle and Regular Maintenance tasks both say the task isn't running -- and that the "last run result" was "The process terminated unexpectedly." (0x8007042B).
    – user541686
    Jul 19, 2014 at 21:22
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    In fact it looks like the explanation you got is completely bogus, because I just ran that task on demand (after some trickery to make it possible) and those tasks just spawned a bunch of new processes like NGEN, Windows Defender, etc... but the SYSTEM process was unaffected. So those tasks are actually irrelevant.
    – user541686
    Jul 19, 2014 at 21:33

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