Sunday, October 4, 2009

VMware Performance Tuning - Linux Guest

Linux guests' performance may be improved if they have been created without much thought.
  • Always use a single VCPU when the CPU capacity requirement of the VM allows it.
  • Install VMware Tools and keep it updated.
  • Add the options "nosmp noapic nolapic clock=pit" to the guest's kernel (2.6) parameters. Don't add "nosmp" if using more than one VCPU.Note clock=pit is depracted since kernel 2.6.16. Use clocksource=pit instead if your kernel is newer than that.
  • On RHEL 5.1 (and variants such as CentOS 5.1) add the option divider=10 to the kernel boot parameters. This causes the default clock tick rate, 1000HZ to be divided by 10, so HZ=100. On other distros, try using a kernel with Hz=100. Most 2.6 desktop distros are using HZ=1000, while the server distros tend to use HZ=100 or HZ=250.

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