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Configuring CPU resources for virtual machines, Virtual Server 2005

    Question

  • I read this article, but I'm still unclear about the total CPU that can be theretically consumed by a VM...
    http://www.microsoft.com/technet/prodtechnol/virtualserver/2005/proddocs/vs_operate_using_perfTune_tune.mspx?mfr=true

    In the article it says the following:

    "Although there is no processor affinity—meaning that individual CPUs are not assigned to individual virtual machines—the maximum that you can allocate to any given virtual machine is 100 percent of one CPU. If you want to allocate the equivalent of one entire CPU to a virtual machine, specify 100 percent as its reserved capacity."

    Let's look at an example

    I have a server running
    2x Dual Core Xeon 5130s, totaling 12GHz

    If I allocate an entire 100% of one CPU to my VM, is it going to be utilizing both cores?
    And if it's unable to use more than 1 core, what happens when it reaches 100% capacity?

    I want to allocate as much CPU as possible to a particular VM, and one 3GHz core is not enough...

    Also, how does Virtual Server 2005 compare with Virtual PC 2007
    Sunday, August 12, 2007 3:20 PM

Answers

  •  2Oldschool wrote:


    Let's go back to my example...

    2x Dual Core Xeon 5130's, totaling 12GHz

    While allocating CPU to a VM, is it going to be maxed at one core per VM? or am I going to have the OpenVZ flexibility, where there is no strict CPU allocation?


     

    A dual socket, dual core server has 4 threads of execution. A 4 VM with 4 virtual processors will make use of all 4 threads of execution, multiple VMs with 4 virtual procs can be created and execute on that system at the same time (perf obviously depends on the workload within the VMs).

    So, the max of each virtual processor's computing power maps to the computing power of the underlying hardware thread on the physical CPUs (minus overhead). That means there is aggregated computing power within the virtual machine the same way as you would find it in the physical world. It is not 1 Uber-CPU per VM that has aggregated computing power.

     

     

      

    Monday, August 13, 2007 3:10 PM
  • Windows Server virtualization is not included in the Beta 3 release. The beta release of the virtualization technologies will be included in the RTM release of Windows Server 2008.

    Thursday, August 16, 2007 10:19 PM

All replies

  •  2Oldschool wrote:


    I have a server running
    2x Dual Core Xeon 5130s, totaling 12GHz

    If I allocate an entire 100% of one CPU to my VM, is it going to be utilizing both cores?

     

    No - virtual machines created with Virtual Server are single-core.

     

     2Oldschool wrote:

    And if it's unable to use more than 1 core, what happens when it reaches 100% capacity?

     

    The VM becomes compute bound and slows down, much as you would see on a maxed out single processor hardware box. In this case, you would see CPU utilization in the host just above 25% (1 core of a 4 core system is maxed out).

     

     2Oldschool wrote:

    I want to allocate as much CPU as possible to a particular VM, and one 3GHz core is not enough...

     

    Windows Server virtualization will include support for workloads with up to 4 virtual cores in the guest.

     

     2Oldschool wrote:

    Also, how does Virtual Server 2005 compare with Virtual PC 2007

     

    Virtual PC is a single threaded Win32 application, where all VM's run under a single process - it also has a standard Windows UI. Virtual Server is a multi-threaded Windows service, where each VM spawns a separate process. It has a web-based management UI.

    Sunday, August 12, 2007 4:44 PM

  • Windows Server virtualization will include support for workloads with up to 4 virtual cores in the guest.



    Sorry, can you elaborate on this a little.....will include?  Is it part of the Beta Download?


    Please link me to the description or documentation of this component.


    "Virtual Cores" sounds suspicios...what about phisical cores?

    Sunday, August 12, 2007 5:38 PM
  • Windows Server virtualization, code-named Viridian, is Microsoft's next generation virtualization platform, which will include support for both 32-bit as well as 64-bit virtual machines, large memory support within the VM, multi-core support, and a new high-performance hardware sharing architecture. While the information on the main Microsoft website, there are in-depth architectural discussions at this link - http://www.microsoft.com/whdc/winhec/2007/pres.mspx.

     

    We're making a distinction between virtual cores and virtual processors. The virtual machine will show up to 4 processors, which are actually multiple cores on a processor. There should be no performance difference between the two.

    Sunday, August 12, 2007 7:39 PM
  •  Mike Sterling [MSFT] wrote:

     

    We're making a distinction between virtual cores and virtual processors. The virtual machine will show up to 4 processors, which are actually multiple cores on a processor. There should be no performance difference between the two.



    "Virtual processors" is a vague concept.

    It sounds to me like it's going to be doing a similar thing with Virtual Server 2005

    Let's go back to my example...

    2x Dual Core Xeon 5130's, totaling 12GHz

    While allocating CPU to a VM, is it going to be maxed at one core per VM? or am I going to have the OpenVZ flexibility, where there is no strict CPU allocation?


    Monday, August 13, 2007 4:43 AM
  •  2Oldschool wrote:


    Let's go back to my example...

    2x Dual Core Xeon 5130's, totaling 12GHz

    While allocating CPU to a VM, is it going to be maxed at one core per VM? or am I going to have the OpenVZ flexibility, where there is no strict CPU allocation?


     

    A dual socket, dual core server has 4 threads of execution. A 4 VM with 4 virtual processors will make use of all 4 threads of execution, multiple VMs with 4 virtual procs can be created and execute on that system at the same time (perf obviously depends on the workload within the VMs).

    So, the max of each virtual processor's computing power maps to the computing power of the underlying hardware thread on the physical CPUs (minus overhead). That means there is aggregated computing power within the virtual machine the same way as you would find it in the physical world. It is not 1 Uber-CPU per VM that has aggregated computing power.

     

     

      

    Monday, August 13, 2007 3:10 PM
  • Could you please confirm that this functionality is currently part of the the Beta download that is available on the site.


    Tuesday, August 14, 2007 6:56 AM
  • Windows Server virtualization is not included in the Beta 3 release. The beta release of the virtualization technologies will be included in the RTM release of Windows Server 2008.

    Thursday, August 16, 2007 10:19 PM
  • The virtualization stuff is not in Beta 3. Is it in the current Release Candidate (RC0)?

    http://msdn2.microsoft.com/en-us/evalcenter/bb383571.aspx

    Tuesday, October 09, 2007 3:56 PM
  • If I am running the CTP version in RC0, am I going to have to complete wipe the system and start over when RTM is released?  Or will there be an upgrade path?

     

    BTW, I currently testing a configuration where all 3 VMs are set for -eight- virtual processors (no reservation of capacity) on my dual quad-core system.  Seems to be working well.

    Sunday, November 04, 2007 12:52 PM
  • Yes - you will need to wipe and reinstall.  We are not supporting upgrades from the CTP.

     

    Cheers,

    Ben

    Monday, November 05, 2007 7:22 PM
  • Would I be able to backup the individual vm files to another disk and restore them into the RTM version?

     

    Just thinking about different avenues to take.  I also saw mentioned that when W2k8 goes to RTM, the virtualization will only be a beta version.  That usually means that there will be no upgrade path for that version either.  Is that assumption correct?

     

    Thanks.

    Monday, November 05, 2007 8:01 PM
  • There will be no supported way to go from the WSv CTP to the WSv beta.  You might be able to move the .VHDs and setup the VMs manually - but we are not testing this and provide no guarantees on your success in doing this.

     

    Cheers,

    Ben

    Tuesday, November 06, 2007 6:42 PM