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From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Stephane Eranian <eranian@google.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	x86 <x86@kernel.org>, Ashok Raj <ashok.raj@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ricardo Neri <ricardo.neri@intel.com>,
	iommu@lists.linux-foundation.org,
	Andi Kleen <andi.kleen@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable
Date: Fri, 7 Jun 2019 07:14:16 -0700
Message-ID: <20190607141416.GA30499@ranerica-svr.sc.intel.com> (raw)
In-Reply-To: <CABPqkBQP=JxpiQE7SVuJO3xPWvsFbAPj916RTYUgaMBDG1OdaQ@mail.gmail.com>

On Thu, Jun 06, 2019 at 05:35:51PM -0700, Stephane Eranian wrote:
> Hi Ricardo,

Hi Stephane,

> Thanks for your contribution here. It is very important to move the
> watchdog out of the PMU wherever possible.

Indeed, using the PMU for the hardlockup detector is still the default
option. This patch series proposes a new kernel command line to switch
to use the HPET.

> 
> On Thu, May 23, 2019 at 6:17 PM Ricardo Neri
> <ricardo.neri-calderon@linux.intel.com> wrote:
> >
> > The HPET-based hardlockup detector relies on the TSC to determine if an
> > observed NMI interrupt was originated by HPET timer. Hence, this detector
> > can no longer be used with an unstable TSC.
> >
> > In such case, permanently stop the HPET-based hardlockup detector and
> > start the perf-based detector.
> >
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > ---
> >  arch/x86/include/asm/hpet.h    | 2 ++
> >  arch/x86/kernel/tsc.c          | 2 ++
> >  arch/x86/kernel/watchdog_hld.c | 7 +++++++
> >  3 files changed, 11 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/hpet.h b/arch/x86/include/asm/hpet.h
> > index fd99f2390714..a82cbe17479d 100644
> > --- a/arch/x86/include/asm/hpet.h
> > +++ b/arch/x86/include/asm/hpet.h
> > @@ -128,6 +128,7 @@ extern int hardlockup_detector_hpet_init(void);
> >  extern void hardlockup_detector_hpet_stop(void);
> >  extern void hardlockup_detector_hpet_enable(unsigned int cpu);
> >  extern void hardlockup_detector_hpet_disable(unsigned int cpu);
> > +extern void hardlockup_detector_switch_to_perf(void);
> >  #else
> >  static inline struct hpet_hld_data *hpet_hardlockup_detector_assign_timer(void)
> >  { return NULL; }
> > @@ -136,6 +137,7 @@ static inline int hardlockup_detector_hpet_init(void)
> >  static inline void hardlockup_detector_hpet_stop(void) {}
> >  static inline void hardlockup_detector_hpet_enable(unsigned int cpu) {}
> >  static inline void hardlockup_detector_hpet_disable(unsigned int cpu) {}
> > +static void harrdlockup_detector_switch_to_perf(void) {}
> >  #endif /* CONFIG_X86_HARDLOCKUP_DETECTOR_HPET */
> >
> This does not compile for me when CONFIG_X86_HARDLOCKUP_DETECTOR_HPET
> is not enabled.
> because:
>    1- you have a typo on the function name
>     2- you are missing the inline keyword

I am sorry. This was an oversight on my side. I have corrected this in
preparation for a v5.

Thanks and BR,
Ricardo
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  reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  1:16 [RFC PATCH v4 00/21] Implement an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 01/21] x86/msi: Add definition for NMI delivery mode Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 02/21] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 03/21] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2019-06-14 15:54   ` Thomas Gleixner
2019-06-14 15:59     ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-06-18 23:13       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes Ricardo Neri
2019-06-14 18:17   ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 05/21] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2019-06-11 19:54   ` Thomas Gleixner
2019-06-14  1:14     ` Ricardo Neri
2019-06-14 16:10       ` Thomas Gleixner
2019-06-18 22:48         ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 06/21] x86/hpet: Configure the timer used by the " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 07/21] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 08/21] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 09/21] x86/nmi: Add a NMI_WATCHDOG NMI handler category Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 10/21] watchdog/hardlockup: Add function to enable NMI watchdog on all allowed CPUs at once Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 11/21] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs Ricardo Neri
2019-06-11 20:11   ` Thomas Gleixner
2019-06-18 22:46     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 13/21] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 14/21] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 15/21] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 16/21] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
2019-06-07  0:35   ` Stephane Eranian via iommu
2019-06-07 14:14     ` Ricardo Neri [this message]
2019-05-24  1:16 ` [RFC PATCH v4 18/21] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2019-06-16  9:55   ` Thomas Gleixner
2019-06-18 22:47     ` Ricardo Neri
2019-06-18 23:15       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 19/21] iommu/vt-d: Rework prepare_irte() to support per-irq " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 20/21] iommu/vt-d: hpet: Reserve an interrupt remampping table entry for watchdog Ricardo Neri
2019-06-16 18:42   ` Thomas Gleixner
2019-06-16 19:21   ` Thomas Gleixner
2019-06-17  8:25     ` Thomas Gleixner
2019-06-17 21:38       ` Stephane Eranian via iommu
2019-06-17 23:08         ` Thomas Gleixner
2019-06-19 15:43           ` Jacob Pan
2019-06-21 15:33             ` Thomas Gleixner
2019-06-21 17:31               ` Jacob Pan
2019-06-21 18:39                 ` Jacob Pan
2019-06-21 20:05                   ` Thomas Gleixner
2019-06-21 23:55                     ` Ricardo Neri
2019-06-22  7:21                       ` Thomas Gleixner
2019-06-18 22:45       ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 21/21] x86/watchdog/hardlockup/hpet: Support interrupt remapping Ricardo Neri
2019-06-16  8:44   ` Thomas Gleixner
2019-06-16  8:53     ` Thomas Gleixner

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