3 Replies Latest reply on May 26, 2008 4:56 PM by wizdude2

    os installation causes excessive host load

    wizdude2 Novice

       

      I've been experimenting with 2.0b2 running under linux on my test box which is a modest celeron 2.8GHz with 2GB of RAM. I configured up a Windows XP and Slackware 12.1 VM which both appeared to run really well.

       

       

      I was then experimenting with a Windows 2003 VM and decided to first make up a slipstreamed version of 2003 with SP2. I used my Windows XP VM to do this. I pushed my ISO up to the host and created a new VM to install 2003.

       

       

      something went wrong in the ISO creation (wrong settings for my ISO9660 filenames) and as a result the windows installer stopped because it was missing a file. It was at this stage that I noticed that my Windows XP and Slackware VM's had idled down and all the CPU power was being used for the Windows 2003 install. The Windows XM VM became almost totally unresponsive and after around 4-5 minutes, the Windows XP VM just "shut down" all by itself.

       

       

      I started to notice a trend with this - whenever I go to install a guest operating system, this new VM sucks all available CPU power and regularly causes the other Windows VM's (sitting idle) to shutdown.

       

       

      All this time my Slackware VM continued to function.

       

       

      My last test was a dummy install of Windows 98 SE (for no real reason ) and I got about half way through the installation and stopped to check everything out. Again, all my CPU power has gone to this new installing VM and the other sessions are almost dead. The load on my box is over 12. I've left it like this all day while I was at work.

       

       

      Once the VM's have completed installation and are up and running, things appear to be ok.

       

       

      My main concern here, however, is that an individual VM can dominate the CPU, completely overload it, starve the other VM's and eventually cause them to shutdown.

       

       

      I'm considering installing vmware server 1.0.5 on this box to compare behaviour.

       

       

      I do realise my hardware isn't all that great. I'm about to drop in a new core2 duo processor into this machine and I might think about the RAM.

       

       

      As a point of comparison, I have an ESX 3.5 box with near identical hardware (except for the cpu - it's a core2 duo 2.66GHz) and it runs fine. I brought up a pile of virtual machines two weeks ago and everything worked perfectly.

       

       

      I realise that vmware server vs esx isn't a valid comparison, but I can't see how vmware server is really usable under these circumstances.

       

       

      cheers, wizdude

       

       

       

       

       

       

       

       

       

        • 1. Re: os installation causes excessive host load
          wizdude2 Novice

          I guess I should also add here: I'm running Slackware 12.1 with a vanilla kernel 2.6.25.4.

           

           

           

           

          I've been scouring the net/forums looking for any reference to specific options that should be set in the kernel for optimum vmware server response, such as recommended values for CONFIG_HZ, CONFIG_IOSCHED, NO_HZ, HIGH_RES_TIMERS, what the preemption model should be.

           

           

           

          Is there a page/guide somewhere that gives recommendations on these?

           

           

           

          the only thing I've found are the vmware server 1.0.5 patches for use with kernel 2.6.25, but they won't apply here. FWIW, all the kernel modules compile and run fine on the host.

           

           

           

          cheers, wizdude

          • 2. Re: os installation causes excessive host load
            Paul Thomas Master

             

            My guess is you are running out of Ram.  I've noticed that once memory has been used, and paging starts, performance drops off dramatically.  Also high disk IO seems to cause problems.  An install could easily hit the disk, in addition cause paging and hence increase disk IO further.

             

             

            One thought, have you tried the install with one or both of the other VM's powered off?

             

             

            Some time ago I was running server 1.x on an athlon 2400 with 1GB Ram, using xp pro as a host.  This could just about run 1 VM, providing the host or guest did not become too busy.  My current config q6600 8GB vista ultimate 64bit, is running 5 VM's well, but pushing it much above that starts to have serious performance issues.

             

             

            Hope this of some use.

             

             

            Paul

             

             

            • 3. Re: os installation causes excessive host load
              wizdude2 Novice

               

              i only partially agree with your comment. i have the box still sitting at high load with no disk activity. it's been idle for over 24 hours now. I have the Windows 98 installation half done at the moment - it's stopped at one of the setup screens (waiting for me to complete the installation - it's not frozen).

               

               

              my box is sitting at a load of 15 with no disk activity at all. swap hasn't been touched. while I haven't done this yet, if I complete the Windows 98 installation or shut this VM down, everything will come back up again.

               

               

              the host isn't thrashing the disk. this issue only occurs during installation. the first time this occurred was with Windows 2003 during one of the initial setup screens in text mode. just having it sit there essentially totally idle occupied all CPU resources.

               

               

              i would understand this if my box was thrashing away that performance would suck, but the box has no disk activity at the moment - just high CPU usage.

               

               

              the same hardware with a different CPU and running ESX 3.5 never experienced the same issues.

               

               

              i see this as some sort of design issue with vmware server, or perhaps there is a dependancy on some kernel configuration. i roll my own kernels and have been using the same configuration on hundreds of other boxes (not running vmware) so there is the possibility that something in my config is conflicting with vmware.

               

               

              i guess my main concern here is that any of the vm's can suddenly request all available cpu power and the other machines will lock and shut down. there doesn't appear to be any way to control this, but under ESX i've never had to since it's never cause me any issues.

               

               

              comments appreciated.

               

               

              cheers, wizdude