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Re: [BUG] Core2 cpu triggers hard lockup with perf test

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [BUG] Core2 cpu triggers hard lockup with perf test
Date 2016-03-01 19:20 +0100
Message-ID <r7X3Q-4gl-31@gated-at.bofh.it> (permalink)
References (4 earlier) <r7TWh-216-7@gated-at.bofh.it> <r7TWi-216-15@gated-at.bofh.it> <r7W7L-3DI-11@gated-at.bofh.it> <r7WAO-3OJ-21@gated-at.bofh.it> <r7WU9-4cC-5@gated-at.bofh.it>
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On Tue, Mar 01, 2016 at 07:04:40PM +0100, Jiri Olsa wrote:

> > That's the PERF_GLOBAL_CTRL, right? But it must have succeeded,
> 
> yep, should be this one:
> 
> static void __intel_pmu_enable_all(int added, bool pmi)
> {
>         struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
> 
>         intel_pmu_pebs_enable_all();
>         intel_pmu_lbr_enable_all(pmi);
>  >>>    wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL,
>                         x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask);
> 
> 
> > otherwise the NMI watchdog would never have fired.
> 
> so NMI wouldn't trigger if CPU is inside wrmsr?

Well, anything goes with MSR writes, that's all a magic heap of
micro-code.

But at the very least it did actually enable the counters, otherwise the
counter used for the NMI watchdog could not fire, it too would still be
disabled.

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Thread

[BUG] Core2 cpu triggers hard lockup with perf test Jiri Olsa <jolsa@redhat.com> - 2016-02-27 13:40 +0100
  Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-02-27 15:50 +0100
  Re: [BUG] Core2 cpu triggers hard lockup with perf test Andi Kleen <andi@firstfloor.org> - 2016-02-27 16:50 +0100
  RE: [BUG] Core2 cpu triggers hard lockup with perf test "Liang, Kan" <kan.liang@intel.com> - 2016-02-29 23:20 +0100
    Re: [BUG] Core2 cpu triggers hard lockup with perf test Jiri Olsa <jolsa@redhat.com> - 2016-03-01 08:00 +0100
    Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 10:20 +0100
      Re: [BUG] Core2 cpu triggers hard lockup with perf test Jiri Olsa <jolsa@redhat.com> - 2016-03-01 12:10 +0100
        Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 12:30 +0100
        Re: [BUG] Core2 cpu triggers hard lockup with perf test Andi Kleen <andi@firstfloor.org> - 2016-03-01 16:00 +0100
          Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 16:00 +0100
            Re: [BUG] Core2 cpu triggers hard lockup with perf test Jiri Olsa <jolsa@redhat.com> - 2016-03-01 18:20 +0100
              Re: [BUG] Core2 cpu triggers hard lockup with perf test Andi Kleen <andi@firstfloor.org> - 2016-03-01 18:40 +0100
              Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 18:50 +0100
                Re: [BUG] Core2 cpu triggers hard lockup with perf test Jiri Olsa <jolsa@redhat.com> - 2016-03-01 19:10 +0100
                Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 19:20 +0100
              Re: [BUG] Core2 cpu triggers hard lockup with perf test Peter Zijlstra <peterz@infradead.org> - 2016-03-01 19:20 +0100
                [PATCH] perf x86: Use PAGE_SIZE for PEBS buffer size on Core2 Jiri Olsa <jolsa@redhat.com> - 2016-03-01 20:10 +0100

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