25% Idle CPU Load

R

RCH1708

Bit poster
I'm running Windows 8.1 on Parallels 9 on OSX 10.9.4. The Windows VM has been consuming a huge amount of CPU power, causing the fan to run constantly on my MB Air. To determine the root of the problem I have disable all non-Microsoft services and startup programs under Windows. As a result Windows task monitor reports an idle CPU load of 1%. However this equates to a pretty constant 25% CPU load for the prl_vm_app measured by OSX.

My Mac has an i7, so I suppose that the prl_vm_app is constantly running one CPU. Whatever the reason, an idle CPU load of 25% is a significant, useless drain on my battery.

What's the reason for this high idle CPU load? Is there something I can do to reduce it (preferably to close to nothing?)

Thanks in advance!
 
Look at Windows Task manager (make sure you show all processes). Sort by cpu descending and see what program is doing the drain.
 
AlekseyM said:
Look at Windows Task manager (make sure you show all processes). Sort by cpu descending and see what program is doing the drain.
Click to expand...

With all processes revealed Windows is only using 1% cpu load. The question is, what's using the other 24%?
 
RCH1708 said:
With all processes revealed Windows is only using 1% cpu load. The question is, what's using the other 24%?
Click to expand...

Are you only allotting one CPU? If so, that might be the problem. Windows is not very good at doing single-cpu stuff anymore. I recommend at least 2. Don't forget that you have cores, so 2 cpu cores on a dual-core machine gives you 2 left for osx host.

Also there is no true cpu affinity in parallels, so if the cores aren't used, mac os eats them (which is good, basically you shouldn't see slow downs on the mac when you assign 2).
 
I allocated 2 cpu's & 4 Gb ram. Is weird because there doesn't seem to be anything running on Windows.

Thanks for your ideas!
 
Yeah something else is up. I have 0-1% most of the time.

Is it Win8? If so, Win8 runs scheduled tasks (win updates/optimizations) that do not show up on taskmgr. When you are in Windows put your mouse over the little flag in the taskbar and see if anything is running.
 
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