13 Replies Latest reply on Jun 3, 2009 5:48 PM by E8500

    How to set Power.CpuPolicy to "dynamic"?

    E8500 Novice

       

      I've upgrade my ESXi 3 server to ESXi 4.

       

       

      I'm trying to change CPU power management policy to utilize Dynamic Voltage and Frequency Scaling(DVFS) as discrived in vSphere Resource Management Guide.

       

       

      It states that to set the CPU power management policy for DVFS, set the advanced host attribute Power.CpuPolicy to "dynamic".

       

       

      However, I tryed to to set Power.CpuPolicy from vsphere Client, it made a error dialog, "The value entered is not valid. Enter another value."

       

       

      I would like to know how to set  Power.CpuPolicy to "dynamic"?

       

       

      Thank you

       

       

        • 1. Re: How to set Power.CpuPolicy to "dynamic"?
          AndreTheGiant Guru User Moderators vExpert

          Do your hardware support this feature?

          Sometimes you must enable in BIOS.

           

          Andre

          **if you found this or any other answer useful please consider allocating points for helpful or correct answers

          • 2. Re: How to set Power.CpuPolicy to "dynamic"?
            E8500 Novice

             

            Thank you for your answer.

             

             

            I've checked the hardware spec. and BIOS settings.

             

             

            I confirmed that CPU and motherboard have Enhanced Intel speed step technology, and the BIOS setting of it is enabled.

             

             

            CPU: Core2Duo E8500

             

             

            Motherboard: Elite G33T-M2

             

             

            Have you set Power.CpuPolicy to "dynamic" successfully?

             

             

             

             

             

            • 3. Re: How to set Power.CpuPolicy to "dynamic"?
              AndreTheGiant Guru User Moderators vExpert

              Have you set Power.CpuPolicy to "dynamic" successfully?

              Not yet, cause I'm not using VS4 in production.

              And in my testing environment I do not have CPU with this function. 

               

              Andre

              **if you found this or any other answer useful please consider allocating points for helpful or correct answers

              • 4. Re: How to set Power.CpuPolicy to "dynamic"?
                dorofeev Novice

                 

                If you got an error when setting Power.CpuPolicy property to "dynamic", then it means that your system does not have proper support for DVFS.  What do you see under "Configuration" tab when you click on "Processor" section?  There should be new field called "Hardware Support" which should say what type of power management hardware support was detected.  Also, make sure your server has power management enabled in the BIOS.  In general, power management (DVFS) is supported on Intel Core family of CPUs and on AMD Greyhound/Barcelona and newer. 

                 

                 

                • 5. Re: How to set Power.CpuPolicy to "dynamic"?
                  E8500 Novice

                   

                  Thank you for your answer!

                   

                   

                  I've update the BIOS, then ESXi recognize Enhanced Speed Step functionality on the configration tab.

                   

                   

                  Of course, I've successfully set Power.CpuPolicy to "dynamic".

                   

                   

                  However,  total wattage of my server doesn't decrease, even all of VMs are suspended.:( 

                   

                   

                  • 6. Re: How to set Power.CpuPolicy to "dynamic"?
                    LucasAlbers Expert

                     

                    I have 3 dell r905 servers running esxi and 4.0 with dynamic policy set.  4.0 uses 40% less power (watts) at it's current idle load.

                     

                     

                    esxi 3.5: 420 - 429

                     

                     

                    esxi 3.5: 385 - 399

                     

                     

                    esxi 4.0 with dynamic power policy: 259 - 280.

                     

                     

                    (259 * 2) / (420 + 385) = 0.643478261

                     

                     

                    That is amazing, and trivial to enable.

                     

                     

                    YMMV depending on your load.

                     

                     

                     

                     

                     

                    1 person found this helpful
                    • 7. Re: How to set Power.CpuPolicy to "dynamic"?
                      dorofeev Novice

                      That's not unexpected at all.  Depending on the processor type and model, decreasing CPU frequency when processor is idle may or may not provide any power savings. Many recent Intel processors support C1E state, which automatically reduces core frequency when the whole package is idle (all cores are idle).  This means that reducing frequency using DVFS algorithm in ESX when package is relatively idle is not going to help since the hardware is already doing it.  However, even on those systems, you can still expect to see some power savings when there is some load.  C1E only works in cases when packages are almost completely idle, and DVFS algorithm in ESX can help to save power when load is somewhere below 60% (which is a configurable threshold by the way).  DVFS will continously monitor CPU utilization and make sure that core frequency is not unnecessarily higher than what is currently required.  So, for example, if CPU utilization is 25% when CPU is running with its highest frequency, ESX can reduce frequence almost in half thus potentially increasing CPU utilization to 50% but still leaving enough headroom for sudden changes in CPU load.  DVFS algorithm used in ESX is very conservative, and it aims to save power while not affecting performance.  Hope this helps.

                      1 person found this helpful
                      • 8. Re: How to set Power.CpuPolicy to "dynamic"?
                        dorofeev Novice

                        Lucas: That's really good to hear!  Can you please tell what processors do these Dell R905 systems have?  Do they have quad-core AMD Barcelonas?

                        • 9. Re: How to set Power.CpuPolicy to "dynamic"?
                          LucasAlbers Expert

                           

                          quad core amd opteron 8380

                           

                           

                           

                           

                           

                          • 10. Re: How to set Power.CpuPolicy to "dynamic"?
                            E8500 Novice

                             

                            To be correct, my Intel Core2Duo E8500 processor server decreases power consumption 1 or 2% as follows.

                             

                             

                               static: 123W

                             

                             

                               dynamic: 121W

                             

                             

                               4VMs working at 5% total cpu usage.

                             

                             

                            I understand that Core2Due E8500 do power saving very well by itself even ESXi is "static". 

                             

                             

                            I know 1 or 2% is very important for huge instragions like a datacenter.

                             

                             

                             

                             

                             

                            • 11. Re: How to set Power.CpuPolicy to "dynamic"?
                              dorofeev Novice

                              Correct.  The C1E enhancement is doing pretty good job of saving power on CPUs that are mostly idle. If you're interested, try disabling C1E in the BIOS (some systems let you do that) and measure idle power with C1E off.

                              • 12. Re: How to set Power.CpuPolicy to "dynamic"?
                                LucasAlbers Expert

                                 

                                What happens if you turn all the vm's off?

                                 

                                 

                                Then what does the power usage show?

                                 

                                 

                                Are you limiting the vm's to only run on a  subset of the cpu's?

                                 

                                 

                                 

                                 

                                 

                                • 13. Re: How to set Power.CpuPolicy to "dynamic"?
                                  E8500 Novice

                                   

                                  If I turn all of VMs off, the power usage is down to 115w and the difference between "dynamic" and "static" disappear.

                                   

                                   

                                  I don't limit cpu resource for any VMs.