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

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: tip.today - scheduler bam boom crash (cpu hotplug)
Date 2017-03-01 15:20 +0100
Message-ID <tgdgK-4b6-17@gated-at.bofh.it> (permalink)
References (5 earlier) <tfwls-86h-15@gated-at.bofh.it> <tfFf3-5LI-3@gated-at.bofh.it> <tfL18-1He-19@gated-at.bofh.it> <tfLaO-1Kw-11@gated-at.bofh.it> <tgcE1-3Ip-3@gated-at.bofh.it>
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On Wed, Mar 01, 2017 at 09:39:18PM +0800, Wanpeng Li wrote:
> 2017-02-28 16:11 GMT+08:00 Wanpeng Li <kernellwp@gmail.com>:
> > 2017-02-28 16:08 GMT+08:00 Peter Zijlstra <peterz@infradead.org>:
> >> On Tue, Feb 28, 2017 at 09:51:07AM +0800, Wanpeng Li wrote:
> >>> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> >>> index 4e95b2e..ed8eda4 100644
> >>> --- a/arch/x86/kernel/cpu/amd.c
> >>> +++ b/arch/x86/kernel/cpu/amd.c
> >>> @@ -557,7 +557,7 @@ static void early_init_amd(struct cpuinfo_x86 *c)
> >>>          set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
> >>>          if (check_tsc_unstable())
> >>>              clear_sched_clock_stable();
> >>> -    } else {
> >>> +    } else if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
> >>>          clear_sched_clock_stable();
> >>>      }
> >>
> >> That's wrong, you can have HYPERVISOR and still use
> >> native_sched_clock() (lguest does that for one).
> >
> > My posting delay to check this in tsc_init().
> 
> Does it make sense?

It makes confusion from where I'm sitting. Please look at that latest
patch I send. I think it should work, but in case you have doubts, try
and find the holes.

  http://lkml.kernel.org/r/20170228080855.GV6515@twins.programming.kicks-ass.net

That marries the sched_clock stable to the existing TSC stable machinery
and removes a bunch of quirks.

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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) Wanpeng Li <kernellwp@gmail.com> - 2017-03-01 14:40 +0100
                Re: tip.today - scheduler bam boom crash (cpu hotplug) Peter Zijlstra <peterz@infradead.org> - 2017-03-01 15:20 +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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