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Groups > linux.kernel > #1588655

Re: tip.today - scheduler bam boom crash (cpu hotplug)

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: tip.today - scheduler bam boom crash (cpu hotplug)
Date 2017-02-27 14:00 +0100
Message-ID <tft4e-5G3-1@gated-at.bofh.it> (permalink)
References <t1fua-70y-5@gated-at.bofh.it> <t1iim-n0-25@gated-at.bofh.it> <t1l6z-27b-53@gated-at.bofh.it> <tfsKS-5zx-19@gated-at.bofh.it> <tfsUx-5CV-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 27/02/2017 13:43, Peter Zijlstra wrote:
> On Mon, Feb 27, 2017 at 08:30:11PM +0800, Wanpeng Li wrote:
> 
>>> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
>>> index 2a5cafd..542710b 100644
>>> --- a/arch/x86/kernel/kvmclock.c
>>> +++ b/arch/x86/kernel/kvmclock.c
>>> @@ -107,12 +107,12 @@ static inline void kvm_sched_clock_init(bool stable)
>>>  {
>>>         if (!stable) {
>>>                 pv_time_ops.sched_clock = kvm_clock_read;
>>> +               clear_sched_clock_stable();
>>>                 return;
>>>         }
>>>
>>>         kvm_sched_clock_offset = kvm_clock_read();
>>>         pv_time_ops.sched_clock = kvm_sched_clock_read;
>>> -       set_sched_clock_stable();
>>
>> This results in sched clock always unstable for kvm guest since there
>> is no invariant tsc cpuid bit exposed for kvm guest currently. 
> 
> What the heck is KVM_FEATURE_CLOCKSOURCE_STABLE_BIT /
> PVCLOCK_TSC_STABLE_BIT about then?

It checks that all the bugs in the host have been ironed out, and that
the host itself supports invtsc.

Paolo

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Thread

Re: tip.today - scheduler bam boom crash (cpu hotplug) Wanpeng Li <kernellwp@gmail.com> - 2017-02-27 13:40 +0100
  Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-27 13:50 +0100
    Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 14:00 +0100
      Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 16:40 +0100
        Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 17:30 +0100
          Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-27 17:40 +0100
            Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 18:30 +0100
              Re: tip.today - scheduler bam boom crash (cpu hotplug) Thomas Gleixner <tglx@linutronix.de> - 2017-02-27 19:10 +0100
                Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 20:10 +0100
                Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-28 00:00 +0100
          Re: tip.today - scheduler bam boom crash (cpu hotplug) Wanpeng Li <kernellwp@gmail.com> - 2017-02-28 03:00 +0100
            Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-28 09:10 +0100
              Re: tip.today - scheduler bam boom crash (cpu hotplug) Wanpeng Li <kernellwp@gmail.com> - 2017-02-28 09:20 +0100
        Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-27 17:50 +0100
      Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-27 23:50 +0100
    Re: tip.today - scheduler bam boom crash (cpu hotplug) Wanpeng Li <kernellwp@gmail.com> - 2017-02-27 15:00 +0100
      Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-02-27 15:50 +0100
  Re: tip.today - scheduler bam boom crash (cpu hotplug) Paolo Bonzini <pbonzini@redhat.com> - 2017-02-27 16:10 +0100

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