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    SubjectRe: regression - 2.6.36 -> 2.6.37 - kvm - 32bit SMP guests don't boot
    On 03/04/2011 02:09 PM, Glauber Costa wrote:
    > On Fri, 2011-03-04 at 19:27 +0100, Nikola Ciprich wrote:
    >
    >> Hello Zachary,
    >>
    >>
    >>> You don't see any messages about TSC being unstable or switching
    >>> clocksource after loading the KVM module? And you are not suspending
    >>> the host or anything?
    >>>
    >> no messages, no suspending, nothing.
    >>
    >>
    >>
    >>> Can you try using "processor.max_cstate=1" on the host as a kernel
    >>> parameter and see if it makes a difference?
    >>>
    >> I tried it, no change..
    >> n.
    >>
    > Zach,
    >
    > I don't understand 100 % the logic behind all your tsc changes.
    > But kvm-clock-wise, most of the problems we had in the past were related
    > to the difference in resolution between the tsc and the host clocksource
    > (hpet, acpi_pm, etc), which in his case, it is a non-issue.
    >
    > It does seem to me like some compensation logic kicked in, dismantling
    > an otherwise good tsc. He does have nonstop_tsc, which means it can't
    > get any better.
    >
    > One thing I noticed when reading the culprit patch in bisect, is that in
    > vcpu_load(), there were previously a call to
    >
    > kvm_request_guest_time_update(vcpu)
    >
    > that was removed without a counterpart addition. Any idea about why it
    > was done?
    >

    That's probably the source of the bug... I've been looking for that
    exact line, though, and I can't find it missing.


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