Difference between revisions of "Xen 4.2 Limits"

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* Maximum of 32K interrupts and 2k PCI segments: this limits the number of devices that can be
 
* Maximum of 32K interrupts and 2k PCI segments: this limits the number of devices that can be
 
used in two ways.
 
used in two ways.
* The number of devices many can be attached to the system must fit into 2k PCI segments, i.e. 2k * 256 [buses] * 32 [devices] * 8 [functions])
+
** The number of devices many can be attached to the system must fit into 2k PCI segments, i.e. 2k * 256 [buses] * 32 [devices] * 8 [functions])
 
** The number of hardware interrupts they may surface (one would expect at least one interrupt per device function, so this is the stricter of the two limitations).
 
** The number of hardware interrupts they may surface (one would expect at least one interrupt per device function, so this is the stricter of the two limitations).

Revision as of 16:52, 13 August 2012

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This is a work in progress. Feel free to add requests for more to the talk page or add additional information here


This document contains information about limits of Xen 4.2.

CPUs & Memory

  • Xen can scale up to 4,095 host CPUs with 5Tb of RAM.
  • Using Para Virtualization (PV), Xen supports a maximum of 512 VCPUs with 512Gb RAM per guest.
  • Using Hardware Virtualization (HVM), Xen supports a maximum of 128 VCPUs with 512Gb RAM per guest.

Other Limits

  • Maximum of 32K interrupts and 2k PCI segments: this limits the number of devices that can be

used in two ways.

    • The number of devices many can be attached to the system must fit into 2k PCI segments, i.e. 2k * 256 [buses] * 32 [devices] * 8 [functions])
    • The number of hardware interrupts they may surface (one would expect at least one interrupt per device function, so this is the stricter of the two limitations).