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Matt McSpirit on Virtualisation, Management and Core Infrastructure

Seeing Core Parking in action

Seeing Core Parking in action

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One of the new capabilities of Windows Server 2008 R2, and Windows 7, is Core Parking.


As we move closer to the release of Windows Server 2008 R2, and combine this with the innovation in CPU technologies that Intel and AMD are producing, it’s clear that CPU’s are getting more powerful, more capable, more-core-heavy (6 and 8 core chips are either here, or imminent) and more efficient, yet we need to ensure that the OS that is running on these CPU’s can take advantage of these CPU improvements.  I’m pleased to say that the R2/7 wave of technologies are right on the money.

As you can see from the diagram, it shows a single quad-core processor, but this could equally be a 6 or 8 core processor.  You can see that 3 of the 4 cores on this chip are ‘inactive’, or ‘parked’.  This means that those cores aren’t using as much power, and thus, the overall power consumption of that server is decreased.  Now, I’m not going to say that this is going to change the world and cut your electricity bills buy 2/3rd’s, but every little helps in a very green-focused climate.  Best thing about it is, it’s just there, in the OS, managed by the Kernel.

So, as an example, if I’ve got a number of VMs, running on a host, and those VM’s resource needs, from a CPU perspective, could easily be handled by fewer cores than I have in my box, the OS will ‘move’ processing for those VMs onto the fewer cores, and ‘park’ the spare ones, giving some power back to the server.  Again, the amount won’t be huge, but over a period of months, it will add up to be a noticeable difference I’m sure, however at the end of the day, it’s an OS capability, so you’re not buying the power related features.

Don’t worry though – resuming from ‘parked’ isn’t like resuming your laptop from sleep – this is practically instant resuming!

It doesn’t just stop there – Windows Server 2008 R2 also provides reduced processor power consumption by adjusting processor speed:

Windows Server 2008 R2 has the ability to adjust the ACPI “P-states” of processors and subsequently adjust server power consumption. ACPI “P-states” are the processor performance states within the ACPI specification. Depending on the processor architecture, Windows Server 2008 R2 can adjust the “P-states” of individual processors and provide very fine control over power consumption.

There’s a nice example of that here.

How can you see Core Parking?  Well, if you open up Resource Monitor, click on the CPU tab, adjust your view appropriately, and viola, check out the parking on that!


This is a 16 core (4 x quad core) box, running 5 (pretty idle) VMs, but still, only 2 of my 16 cores are active at this point in time, and you have to have a minimum of 1, so that isn’t bad!  It might not always be the same 2 – it will fluctuate from time to time, but still, it gives you a good idea that something is happening, and that little something will save you money, and improve your green credentials, and, like a hell of a lot of other things, it’s just out of the box with Windows Server 2008 R2, regardless of Hyper-V virtualisation.

Top stuff.

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  • Matt McSpirit:Hot on the heels of my post a couple of days back, about Core Parking , I’d like to add to that, some information around some of the other CPU-related enhancements that are coming in the R2 wave.

  • Yes, When will we be able to remove this option. I have a desktop I7 8 cores, and sometimes my Quad Core runs faster.

  • Hi Gates,

    I'd be suprised if your Quad Core runs faster - Core Parking only kicks in when the cores aren't required, so if you were running an app that needed all the cores, this wouldn't be the case.

    You may find the information here: useful.



  • I need to experiment with core parking, which laptops support this feature.  I would like to get both an AMD and Intel based multicore system taht supports core parking under windows 7

  • Disabling CPU Parking is the best thing I've done for my i7 computer. It really improves performance. (i7 920, 6 Gigs DDR3, ATI 5770, Desktop Computer running Win 7 x64).

    I like to share my experience

    I tried 3 applications:

    DIRT 2: Now I can max out all Graphics at 1080p, and gained an extra 20 FPS!!. Frame rate became far more stable (sudden frame rates drops dissapeared),

    Heaven Benchmark 2.1: Now I can run decent tessellation ( Catalyst 10.5 also helped ) and got an average of 10fps more out of it.

    Visual Studio 2010: It might be only my impression but builds are faster (140.000+ lines of source code), XAML rendering and Intellisense work smoother.

    Overall disabling this feature on Desktop computers is a Must!!

  • Nice post! ; just curius about perfomance issues ... the common idea in the web it's that CP means a "degraded performance for less power consuption" compromise ... .i understand that CP work when the system is iddle or with low load .. but maybe the transition from full cores working to some parked and back isn't that good for performance???

    Maybe we need a blog post to set the record straight

    Ahh you have a broken link -> "There’s a nice example of that here." -> -> 404 Error

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