From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
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 12/23] kernel/watchdog: Introduce a struct for NMI watchdog operations
Date: Thu, 14 Jun 2018 19:21:12 -0700 [thread overview]
Message-ID: <20180615022112.GE11625@voyager> (raw)
In-Reply-To: <20180614123250.230667f6@roar.ozlabs.ibm.com>
On Thu, Jun 14, 2018 at 12:32:50PM +1000, Nicholas Piggin wrote:
> On Wed, 13 Jun 2018 18:31:17 -0700
> Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote:
>
> > On Wed, Jun 13, 2018 at 09:52:25PM +1000, Nicholas Piggin wrote:
> > > On Wed, 13 Jun 2018 11:26:49 +0200 (CEST)
> > > Thomas Gleixner <tglx@linutronix.de> wrote:
> > >
> > > > On Wed, 13 Jun 2018, Peter Zijlstra wrote:
> > > > > On Wed, Jun 13, 2018 at 05:41:41PM +1000, Nicholas Piggin wrote:
> > > > > > On Tue, 12 Jun 2018 17:57:32 -0700
> > > > > > Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote:
> > > > > >
> > > > > > > Instead of exposing individual functions for the operations of the NMI
> > > > > > > watchdog, define a common interface that can be used across multiple
> > > > > > > implementations.
> > > > > > >
> > > > > > > The struct nmi_watchdog_ops is defined for such operations. These initial
> > > > > > > definitions include the enable, disable, start, stop, and cleanup
> > > > > > > operations.
> > > > > > >
> > > > > > > Only a single NMI watchdog can be used in the system. The operations of
> > > > > > > this NMI watchdog are accessed via the new variable nmi_wd_ops. This
> > > > > > > variable is set to point the operations of the first NMI watchdog that
> > > > > > > initializes successfully. Even though at this moment, the only available
> > > > > > > NMI watchdog is the perf-based hardlockup detector. More implementations
> > > > > > > can be added in the future.
> > > > > >
> > > > > > Cool, this looks pretty nice at a quick glance. sparc and powerpc at
> > > > > > least have their own NMI watchdogs, it would be good to have those
> > > > > > converted as well.
> > > > >
> > > > > Yeah, agreed, this looks like half a patch.
> > > >
> > > > Though I'm not seeing the advantage of it. That kind of NMI watchdogs are
> > > > low level architecture details so having yet another 'ops' data structure
> > > > with a gazillion of callbacks, checks and indirections does not provide
> > > > value over the currently available weak stubs.
> > >
> > > The other way to go of course is librify the perf watchdog and make an
> > > x86 watchdog that selects between perf and hpet... I also probably
> > > prefer that for code such as this, but I wouldn't strongly object to
> > > ops struct if I'm not writing the code. It's not that bad is it?
> >
> > My motivation to add the ops was that the hpet and perf watchdog share
> > significant portions of code.
>
> Right, a good motivation.
>
> > I could look into creating the library for
> > common code and relocate the hpet watchdog into arch/x86 for the hpet-
> > specific parts.
>
> If you can investigate that approach, that would be appreciated. I hope
> I did not misunderstand you there, Thomas.
>
> Basically you would have perf infrastructure and hpet infrastructure,
> and then the x86 watchdog driver will use one or the other of those. The
> generic watchdog driver will be just a simple shim that uses the perf
> infrastructure. Then hopefully the powerpc driver would require almost
> no change.
Sure, I will try to structure code to minimize the changes to the powerpc
watchdog... without breaking the sparc one.
Thanks and BR,
Ricardo
next prev parent reply other threads:[~2018-06-15 2:24 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 [this message]
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
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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