Core Parking

[Weltschmerz]

Hey folks!

Today I stumbled upon a Win7 energy saving feature known as "Core Parking". What it does is that, depending on the CPU´s state (idle, load), this feature would temporarily "park" some cores and instead just let 1 core do the work in order to save energy etc.
The problem arises, as soon as the system gets under load again, as the sudden "unparking" of the resting cores can/will lead to performance spikes. This is just very generally speaking and from feedback, most people experienced overall better system performance (games, apps) upon disabling this feature.

Now I was amazed that I didn´t find anything related to "Core Parking" here so I was wondering if any of you guys know about that.
It obviously affects multi-core processors and seems to be specifically only affecting the Intel iCore CPUs w/ HT and also the AMD FX ones. I´m not sure about the Phenom II CPUs though, most likely not.
There are some registry tweaks out there, which turn off this feature and even certain apps that detect "parked" cores and permanently enable them. This feature is somewhat related to the energy saving options under BIOS and one might say that disabling those would already do the job, however people still had "parked" cores after all.

To see, whether you have "parked" cores or not, got to Task Manager -> Performance tab -> Performance monitor -> CPU tab.

 

[Ed1]

this might give more info .

http://bitsum.com/about_cpu_core_parking.php

 

[Idontcare]

It is true that the topic of "core parking" rarely comes up here in this forum. The only time it tends to get discussed is in matter of running stress-tester programs on CPUs that have hyperthreading.

The issue of "core parking" when using "processor affinity" in Task Manager

If I had to guess I'd venture to say that we probably don't see people talking about core-parking more often because it isn't really a performance issue for the vast majority of folks who visit here.

Whether that is because they simply aren't aware of it or that is because it simply doesn't manifest in a problematic fashion is an unanswerable question.

 

[Ed1]

It is true that the topic of "core parking" rarely comes up here in this forum. The only time it tends to get discussed is in matter of running stress-tester programs on CPUs that have hyperthreading.

The issue of "core parking" when using "processor affinity" in Task Manager

If I had to guess I'd venture to say that we probably don't see people talking about core-parking more often because it isn't really a performance issue for the vast majority of folks who visit here.

Whether that is because they simply aren't aware of it or that is because it simply doesn't manifest in a problematic fashion is an unanswerable question.

Also vast majority don't even know its happening , so that's big part to I guess .

 

[BrightCandle]

Certainly with the most recent cards it seems to cause more problems with AMD cards than NVidia (no idea why that is but having had both parking caused stuttering to be much worse on 2x7970's but on the 680's it makes no measurable difference). But in general those sensitive to these spikes in performance and inconsistent frame rates it causes tend to disable it from a guide elsewhere. Guru3D's forums talk about it a lot.

 

[moonbogg]

I turned off core parking and it made zero measurable difference for gaming FPS. This was a couple months ago and I forgot about that feature since then as it doesn't appear to help with my needs. Maybe someone has more detailed information regarding potential performance benefits?

 

[Weltschmerz]

True, most people probably don´t even know about this.
Not too long ago there was an update for AMD FX and Opteron processors related to core parking, something issues got fixed with it, I don´t know.

People with Intel iCore CPUs reported better performance in BF3 and in some benchmarks from what I´ve read.

 

[AdamK47]

Certainly with the most recent cards it seems to cause more problems with AMD cards than NVidia (no idea why that is but having had both parking caused stuttering to be much worse on 2x7970's but on the 680's it makes no measurable difference). But in general those sensitive to these spikes in performance and inconsistent frame rates it causes tend to disable it from a guide elsewhere. Guru3D's forums talk about it a lot.

Try with three 7970s. The stuttering is much more pronounced. I've had core parking disabled for quite a while. It has eliminated the stutter problem. Don't really care about the energy savings enabling it provides.