Logic behind core parking?

[DeadHead]

I was wondering a little about the logic behind the behavior of core parking. When my computer goes into low performance mode, it should park 4 cores (have 4+4, i7 HT).

From the screeenshot it seems that it will park cores at random, both physical and virtual.

[BenYeeHua]

?
Based on the Image, it is parking 1 of the HT thread, so it did park only 1 of the 2 thread from the core.

As this is Windows 7, it will park the HT thread, not the core, so it is useless(as it cause performance issues while don't save power) for Windows 7 until you upgrade to Windows 8+.
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The image is like this, if you wonder.

|Core 0|Core 0|Core 1|Core 1|Core 2|Core 2|Core 3|Core 3|

[DeadHead]

As far as I can remember, Win 7 doesn't park physical cores by default on a processor with HT. At least that's how I remember it, could be wrong there. But now, when going to power saving mode, it's always different cores that gets parked for some odd reason, and as can be seen, it will park physical as well as virtual cores.

[Jeremy Collake]

As far as I can remember, Win 7 doesn't park physical cores by default on a processor with HT. At least that's how I remember it, could be wrong there. But now, when going to power saving mode, it's always different cores that gets parked for some odd reason, and as can be seen, it will park physical as well as virtual cores.

I believe it depends on the processor. AMD's rendition of HyperThreading, paired core modules, are treated as logical cores, and they and their physical counterparts are certainly parked by default in all power plans, best my experience.

I've attempted to dig deeper into the core parking rabbit hole, and let me tell you there are countless additional hidden variables that control it's behavior. It's therefore not at all inconceivable that some are not tuned properly. In fact, Microsoft has issued Hotfixes in the past to address this very issue.

[Jeremy Collake]

To answer the OP's question:

You can only control how many cores are allowed to be parked per power plan.

The decision as to which cores are parked, and when, is left entirely to the OS and no additional configuration is available to the user at this time.

This is not something Lasso controls. All it can do is what you tell it to do via ParkControl or other - turn on, off, or limit the number of cores that can be parked.