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

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Message-ID: <CANRm+Cy_BOeWkTX+GRrB_kdAY4p2KT7_2G+7tbrEi9pQbt7vXQ@mail.gmail.com>
Date:   Wed, 1 Mar 2017 21:39:18 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Mike Galbraith <efault@....de>,
        LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: tip.today - scheduler bam boom crash (cpu hotplug)

2017-02-28 16:11 GMT+08:00 Wanpeng Li <kernellwp@...il.com>:
> 2017-02-28 16:08 GMT+08:00 Peter Zijlstra <peterz@...radead.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?

Regards,
Wanpeng Li