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From: Nicholas Piggin <npiggin@gmail.com>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <andi.kleen@intel.com>,
	Ashok Raj <ashok.raj@intel.com>, Borislav Petkov <bp@suse.de>,
	Tony Luck <tony.luck@intel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	x86@kernel.org, sparclinux@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Jacob Pan <jacob.jun.pan@intel.com>,
	Don Zickus <dzickus@redhat.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Frederic Weisbecker <frederic@kernel.org>,
	Babu Moger <babu.moger@oracle.com>,
	"David S. Miller" <davem@davemloft.net>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Colin Ian King <colin.king@canonical.com>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	iommu@lists.linux-foundation.org
Subject: Re: [RFC PATCH 14/23] watchdog/hardlockup: Decouple the hardlockup detector from perf
Date: Thu, 14 Jun 2018 11:41:44 +1000	[thread overview]
Message-ID: <20180614114144.05891a04@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20180614011901.GA22652@voyager>

On Wed, 13 Jun 2018 18:19:01 -0700
Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote:

> On Wed, Jun 13, 2018 at 10:43:24AM +0200, Peter Zijlstra wrote:
> > On Tue, Jun 12, 2018 at 05:57:34PM -0700, Ricardo Neri wrote:  
> > > The current default implementation of the hardlockup detector assumes that
> > > it is implemented using perf events.  
> > 
> > The sparc and powerpc things are very much not using perf.  
> 
> Isn't it true that the current hardlockup detector
> (under kernel/watchdog_hld.c) is based on perf?

arch/powerpc/kernel/watchdog.c is a powerpc implementation that uses
the kernel/watchdog_hld.c framework.

> As far as I understand,
> this hardlockup detector is constructed using perf events for architectures
> that don't provide an NMI watchdog. Perhaps I can be more specific and say
> that this synthetized detector is based on perf.

The perf detector is like that, but we want NMI watchdogs to share
the watchdog_hld code as much as possible even for arch specific NMI
watchdogs, so that kernel and user interfaces and behaviour are
consistent.

Other arch watchdogs like sparc are a little older so they are not
using HLD. You don't have to change those for your series, but it
would be good to bring them into the fold if possible at some time.
IIRC sparc was slightly non-trivial because it has some differences
in sysctl or cmdline APIs that we don't want to break.

But powerpc at least needs to be updated if you change hld apis.

Thanks,
Nick

  reply	other threads:[~2018-06-14  1:42 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-13  0:57 [RFC PATCH 00/23] Implement an HPET-based hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 01/23] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 02/23] genirq: Introduce IRQD_DELIVER_AS_NMI Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 03/23] genirq: Introduce IRQF_DELIVER_AS_NMI Ricardo Neri
2018-06-13  8:34   ` Peter Zijlstra
2018-06-13  8:59     ` Julien Thierry
2018-06-13  9:20       ` Thomas Gleixner
2018-06-13  9:36         ` Julien Thierry
2018-06-13  9:49           ` Julien Thierry
2018-06-13  9:57           ` Thomas Gleixner
2018-06-13 10:25             ` Julien Thierry
2018-06-13 10:06         ` Marc Zyngier
2018-06-15  2:12           ` Ricardo Neri
2018-06-15  8:01             ` Julien Thierry
2018-06-16  0:39               ` Ricardo Neri
2018-06-16 13:36                 ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 04/23] iommu/vt-d/irq_remapping: Add support for IRQCHIP_CAN_DELIVER_AS_NMI Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 05/23] x86/msi: " Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 06/23] x86/ioapic: Add support for IRQCHIP_CAN_DELIVER_AS_NMI with interrupt remapping Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 07/23] x86/hpet: Expose more functions to read and write registers Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 08/23] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 09/23] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 10/23] x86/hpet: Relocate flag definitions to a header file Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 11/23] x86/hpet: Configure the timer used by the hardlockup detector Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 12/23] kernel/watchdog: Introduce a struct for NMI watchdog operations Ricardo Neri
2018-06-13  7:41   ` Nicholas Piggin
2018-06-13  8:42     ` Peter Zijlstra
2018-06-13  9:26       ` Thomas Gleixner
2018-06-13 11:52         ` Nicholas Piggin
2018-06-14  1:31           ` Ricardo Neri
2018-06-14  2:32             ` Nicholas Piggin
2018-06-14  8:32               ` Thomas Gleixner
2018-06-15  2:21               ` Ricardo Neri
2018-06-14  1:26       ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 13/23] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 14/23] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2018-06-13  8:43   ` Peter Zijlstra
2018-06-14  1:19     ` Ricardo Neri
2018-06-14  1:41       ` Nicholas Piggin [this message]
2018-06-15  2:23         ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 15/23] kernel/watchdog: Add a function to obtain the watchdog_allowed_mask Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 16/23] watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2018-06-13  5:23   ` Randy Dunlap
2018-06-14  1:00     ` Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 17/23] watchdog/hardlockup/hpet: Convert the timer's interrupt to NMI Ricardo Neri
2018-06-13  9:07   ` Peter Zijlstra
2018-06-15  2:07     ` Ricardo Neri
2018-06-13  9:40   ` Thomas Gleixner
2018-06-15  2:03     ` Ricardo Neri
2018-06-15  9:19       ` Thomas Gleixner
2018-06-16  0:51         ` Ricardo Neri
2018-06-16 13:24           ` Thomas Gleixner
2018-06-20  0:15             ` Ricardo Neri
2018-06-20  0:25               ` Randy Dunlap
2018-06-21  0:25                 ` Ricardo Neri
2018-06-20  7:47               ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 18/23] watchdog/hardlockup/hpet: Add the NMI watchdog operations Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 19/23] watchdog/hardlockup: Make arch_touch_nmi_watchdog() to hpet-based implementation Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 20/23] watchdog/hardlockup/hpet: Rotate interrupt among all monitored CPUs Ricardo Neri
2018-06-13  9:48   ` Thomas Gleixner
2018-06-15  2:16     ` Ricardo Neri
2018-06-15 10:29       ` Thomas Gleixner
2018-06-16  0:46         ` Ricardo Neri
2018-06-16 13:27           ` Thomas Gleixner
2018-06-13  0:57 ` [RFC PATCH 21/23] watchdog/hardlockup/hpet: Adjust timer expiration on the number of " Ricardo Neri
2018-06-13  0:57 ` [RFC PATCH 22/23] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2018-06-13  5:26   ` Randy Dunlap
2018-06-14  0:58     ` Ricardo Neri
2018-06-14  3:30       ` Randy Dunlap
2018-06-13  0:57 ` [RFC PATCH 23/23] watchdog/hardlockup: Activate the HPET-based lockup detector Ricardo Neri

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