5 Replies Latest reply on May 26, 2008 5:25 PM by wizdude2

    CPU info is wrong for HT system + awful performance

    chort Enthusiast

      I'm running Server2 Beta on an older Xeon host with dual hyper-threaded CPUs.

       

      The host OS is Oracle Enterprise Linux 5.1 running the Oracle-updated PAE kernel: 2.6.18-53.0.0.0.1.el5PAE #1 SMP Sat Nov 10 20:52:07 EST 2007 i686 i686 i386 GNU/Linux.

       

      The host reports 4 CPUs at 2.66 GHz each (which is correct).  Here's the cpuinfo for the 4th CPU:

      processor       : 3

      vendor_id       : GenuineIntel

      cpu family      : 15

      model           : 2

      model name      : Intel(R) Xeon(TM) CPU 2.66GHz

      stepping        : 7

      cpu MHz         : 2658.278

      cache size      : 512 KB

      physical id     : 3

      siblings        : 2

      core id         : 0

      cpu cores       : 1

      fdiv_bug        : no

      hlt_bug         : no

      f00f_bug        : no

      coma_bug        : no

      fpu             : yes

      fpu_exception   : yes

      cpuid level     : 2

      wp              : yes

      flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr

      bogomips        : 5315.48

       

      The problem is, when I log into the web console it's reporting the CPUs as

      2 x Intel(R) Xeon(TM) CPU 2.66GHz

      10632.00 MHz (i.e. roughly 4x the clockspeed)

       

      My one configured guest, which works fine in Server1 and was pre-configured for 2 CPUs is showing:

      Processors 2 X 5.191 GHz (i.e. 2x the clockspeed)

       

      The actual guest has been booting up for about 30 minutes now.  Loading the kernel was relatively fast, but as soon as it started loading network service (and updated VMware tools) the performance ground to a screeching halt.

       

      Any ideas?

        • 1. Re: CPU info is wrong for HT system + awful performance
          chort Enthusiast

          PS forgot to mention the guest is CentOS, I believe based off RHEL 5.

          • 2. Re: CPU info is wrong for HT system + awful performance
            sej7278 Enthusiast

            yeah i get the doubled cpu-speed too my my pentium4 ht system thats fedora7, i386 2.6.23 smp

             

            i've got a feeling it says the same on my core2duo laptop - fedora7 x86_64 2.6.20 smp

            • 3. Re: CPU info is wrong for HT system + awful performance
              Go_Adi Novice

              Hint: Make Sure to Disable the cpuspeed service on the host dono how this is called on "oracles Linux"

               

               

              but on CentOS or Redhat do this (on the host not th vm's)

               

              • service cpuspeed stop

              • chkconfig cpuspeed --level 345 off

              • service vmware restart

               

              i had success by stopping the cpuspeed service

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              • 4. Re: CPU info is wrong for HT system + awful performance
                wizdude2 Novice

                 

                I would disable the hyperthreading in the system BIOS. enabling hyperthreading is great for desktop operating systems because they get to use a bit of unused "slack" in the processor, but in this instance, vmware essentially believes you have dual core processors.

                 

                 

                it's generally accepted that high load production servers running linux/unix should have hyperthreading disabled since the threading within the operating system will perform better.

                 

                 

                i've also done a fair bit of reading about the guest systems - assigning two cpu's to a windows vm can cause significant problems in vmware server due to the way windows handles multiple processors. change the guest configuration to a single cpu and i think you'll notice a significant gain in performance.

                 

                 

                remember that your hardware is being virtualised for your environment. there is no reason why a single "virtual" cpu cannot have the performance of multiple cores in a best case scenario.

                 

                 

                cheers, wizdude

                 

                 

                 

                 

                 

                • 5. Re: CPU info is wrong for HT system + awful performance
                  Peter_vm Guru
                  wizdude2 wrote:

                   

                  remember that your hardware is being virtualised for your environment. there is no reason why a single "virtual" cpu cannot have the performance of multiple cores in a best case scenario.

                  There is a reason. VMware application cannot simultaneously engage more host cores than number of virtual processors that has been assigned to the guest.

                  1 person found this helpful