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[Xen-devel] Dom0 Hang for large VCPU counts > PCPU

  • To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Zulauf, John" <john.zulauf@xxxxxxxxx>
  • Date: Wed, 24 Jan 2007 10:56:45 -0800
  • Delivery-date: Wed, 24 Jan 2007 10:56:30 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Acc/6WSeIoDi05TDRUmkOjJugvswfg==
  • Thread-topic: Dom0 Hang for large VCPU counts > PCPU

We have been experimenting with large VCPU counts >> PCPU and have succeeded in hanging Dom0 in or during /sbin/loader.


Using xen-3.0.4-testing with an HVM booting the FC6 DVD on a Core2 Duo (i.e. 2 PCPU) on a 965 chipset


VCPU=17 – works

VCPU=20 – works (takes a very long time)

VCPU=24 – lockup (whole machine, yes I mean Dom0)

VCPU=31 – same

VCPU=32 – same


We’ve noted in the Xen l-apic code a hard 32 CPU limit (a uint32 used as an l-apic (vcpu?) bitmask), but this looks to be unrelated.


John Zulauf

Intel Corporation


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