Maximum number of logical processors supported by the Xen Hypervisor

Updated -

Issue

  • What are the maximum number of logical CPUs (including physical cores and hyperthreads) supported by the Xen hypervisor in Red Hat Enterprise Linux 5?

Environment

  • Red Hat Enterprise Linux 5
  • Xen Hypervisor

Resolution

  • The Xen Hypervisor in Red Hat Enterprise Linux 5.6 (64-bit) supports a maximum of 128 logical processors. 32-bit RHEL is limited to 32 processors.
  • Please refer to http://www.redhat.com/rhel/virtualization/compare/ for the most up to date virtualization limits.

  • If your system has more than 128 logical processors, the hypervisor may hang when booting. To avoid this, add the parameter maxcpus=128 on the Xen kernel command line in /etc/grub.conf. For example:

    title Red Hat Enterprise Linux Server (2.6.18-238.el5xen)
            root (hd0,0)
            kernel /xen.gz-2.6.18-238.el5 maxcpus=128
            module /vmlinuz-2.6.18-238.el5xen ro root=/dev/VolGroup00/TikangaRoot rhgb quiet

  • Component
  • xen

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