Windows 7 core parking added by Matt "mfrobben" http://forum.cakewalk.com/fb.ashx?m=1916167 FYI - Microsoft has a full documentation page on changing power settings in more advanced ways here:
http://www.microsoft.com/whdc/system/pnppwr/default.mspx I have to second manolo and pinguinotuerto's comments below - is there any concrete evidence that core parking negatively affects performance for your application? Unless there's some data behind this I'd be wary of random tunings, especially deleting registry keys. Also, what are you measuring before and after the change other than %CPU? Processors have power states these days that can make %CPU utilization a misleading value - for example it could be at 100% but at a low frequency, implying that the CPU isn't even being taxed to its full extent.
See here----> http://blogs.technet.com/winserverperformance/archive/2009/08/06/interpreting-cpu-utilization-for-performance-analysis.aspx This doc, Power Policy Configuration and Deployment in Windows, explains that the best way to turn off core parking is to use powercfg from the command line: http://download.microsoft.com/download/a/d/f/adf1347d-08dc-41a4-9084-623b1194d4b2/PMPolicy_Windows.docx The registry might be the underlying mechanism which controls the policies, but powercfg is a less error-prone method and faster too - the powercfg command /setactive enables power settings changes right away with no need for a reboot or log off.
"powercfg /qh scheme_current sub_processor" will query the power settings for your current power plan (be it high performance, balanced, or power saver).
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As you mentioned in your post, there's two GUIDs you want. By default, these were set to the following on my machine: Power Setting GUID: 0cc5b647-c1df-4637-891a-dec35c318583 (Processor performance core parking min cores)
Minimum Possible Setting: 0x00000000
Maximum Possible Setting: 0x00000064
Possible Settings increment: 0x00000001
Possible Settings units: %
Current AC Power Setting Index: 0x0000000a
Current DC Power Setting Index: 0x0000000a
Power Setting GUID: ea062031-0e34-4ff1-9b6d-eb1059334028 (Processor performance core parking max cores)
Minimum Possible Setting: 0x00000000
Maximum Possible Setting: 0x00000064
Possible Settings increment: 0x00000001
Possible Settings units: %
Current AC Power Setting Index: 0x00000064
Current DC Power Setting Index: 0x00000064
To set min and max cores for core parking to 0 on AC power (desktop, fixed power supply), the commands would be:
"powercfg /setacvalueindex scheme_current sub_processor 0cc5b647-c1df-4637-891a-dec35c318583 0" "powercfg /setacvalueindex scheme_current sub_processor ea062031-0e34-4ff1-9b6d-eb1059334028 0"
"powercfg /setactive scheme_current"
If you want to set DC power, change /setacvalueindex to /setdcvalueindex.
This won't change the values for other power plans than the one you're currently on. Scheme_current can be replaced with scheme_balanced, scheme_max, or scheme_min to do that.
Cheers,
~Matt