[Bug 65081] New: Starting a second guest with -smp 2 makes the first guest very slow and the second one hang (or also very slow)

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=65081

            Bug ID: 65081
           Summary: Starting a second guest with -smp 2 makes the first
                    guest very slow and the second one hang (or also very
                    slow)
           Product: Virtualization
           Version: unspecified
    Kernel Version: 3.12
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: d.haid@gogi.tv
        Regression: No

I think this first occured when I upgraded the kernel to 3.11 and qemu to
1.6.1. I am now running kernel version 3.12 and the problem still exists.

If I start a first KVM guest with -smp 2 it runs fine. As soon as I start
another KVM guest on the same host also with -smp 2, the first one gets
extremely slow. I can type one character per second via ssh. I do not see any
messages from the second guest, so it seems to hang or is very slow.

If I start the second kVM guest without -smp 2 both guests seem to work fine.

I get the following messages on the host, but I do not know whether they are
relevant.

kvm: SMP vm created on host with unstable TSC; guest TSC will not be reliable

qemu-system-x86: sending ioctl 5326 to a partition!
qemu-system-x86: sending ioctl 80200204 to a partition!

kvm [409]: vcpu0 unhandled rdmsr: 0xc0010001
kvm [409]: vcpu0 unhandled rdmsr: 0x3a

-

It is likely that this is not enough information to find the bug, so I would
appreciate any help on what I can do to obtain more information about what
might be happening here.

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