From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org, Tony Luck <tony.luck@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Stephane Eranian <eranian@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Joerg Roedel <joro@8bytes.org>,
Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
David Woodhouse <dwmw2@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Nicholas Piggin <npiggin@gmail.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Ricardo Neri <ricardo.neri@intel.com>,
iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 01/29] irq/matrix: Expose functions to allocate the best CPU for new vectors
Date: Wed, 11 May 2022 17:09:24 -0700 [thread overview]
Message-ID: <20220512000924.GA16273@ranerica-svr.sc.intel.com> (raw)
In-Reply-To: <878rreh27n.ffs@tglx>
On Fri, May 06, 2022 at 09:48:28PM +0200, Thomas Gleixner wrote:
> Ricardo,
Thank you very much for your feedback Thomas! I am sorry for my late reply, I
had been out of office.
>
> On Thu, May 05 2022 at 16:59, Ricardo Neri wrote:
> > Certain types of interrupts, such as NMI, do not have an associated vector.
> > They, however, target specific CPUs. Thus, when assigning the destination
> > CPU, it is beneficial to select the one with the lowest number of
> > vectors.
>
> Why is that beneficial especially in the context of a NMI watchdog which
> then broadcasts the NMI to all other CPUs?
My intent was not the NMI watchdog specifically but potential use cases that do
not involve NMI broadcasts. If the NMI targets a single CPU, it is best to
select the CPU with the lowest vector allocation count.
>
> That's wishful thinking perhaps, but I don't see any benefit at all.
>
> > Prepend the functions matrix_find_best_cpu_managed() and
> > matrix_find_best_cpu_managed()
>
> The same function prepended twice becomes two functions :)
>
Sorry, I missed this.
> > with the irq_ prefix and expose them for
> > IRQ controllers to use when allocating and activating vector-less IRQs.
>
> There is no such thing like a vectorless IRQ. NMIs have a vector. Can we
> please describe facts and not pulled out of thin air concepts which do
> not exist?
Thank you for the clarification. I see your point. I wrote this patch because
maskable interrupts and NMIs have different entry points. As you state,
however, the also have a vector.
I can drop this patch.
BR,
Ricardo
>
> Thanks,
>
> tglx
next prev parent reply other threads:[~2022-05-12 0:06 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-05 23:59 [PATCH v6 00/29] x86: Implement an HPET-based hardlockup detector Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 01/29] irq/matrix: Expose functions to allocate the best CPU for new vectors Ricardo Neri
2022-05-06 19:48 ` Thomas Gleixner
2022-05-12 0:09 ` Ricardo Neri [this message]
2022-05-05 23:59 ` [PATCH v6 02/29] x86/apic: Add irq_cfg::delivery_mode Ricardo Neri
2022-05-06 19:53 ` Thomas Gleixner
2022-05-12 0:26 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 03/29] x86/apic/msi: Set the delivery mode individually for each IRQ Ricardo Neri
2022-05-06 20:05 ` Thomas Gleixner
2022-05-12 0:38 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 04/29] x86/apic: Add the X86_IRQ_ALLOC_AS_NMI irq allocation flag Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 05/29] x86/apic/vector: Do not allocate vectors for NMIs Ricardo Neri
2022-05-06 21:12 ` Thomas Gleixner
2022-05-13 18:03 ` Ricardo Neri
2022-05-13 20:50 ` Thomas Gleixner
2022-05-13 23:45 ` Ricardo Neri
2022-05-14 8:15 ` Thomas Gleixner
2022-05-05 23:59 ` [PATCH v6 06/29] x86/apic/vector: Implement support for NMI delivery mode Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 07/29] iommu/vt-d: Clear the redirection hint when the destination mode is physical Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 08/29] iommu/vt-d: Rework prepare_irte() to support per-IRQ delivery mode Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 09/29] iommu/vt-d: Set the IRTE delivery mode individually for each IRQ Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 10/29] iommu/vt-d: Implement minor tweaks for NMI irqs Ricardo Neri
2022-05-06 21:23 ` Thomas Gleixner
2022-05-13 18:07 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 11/29] iommu/amd: Expose [set|get]_dev_entry_bit() Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 12/29] iommu/amd: Enable NMIPass when allocating an NMI irq Ricardo Neri
2022-05-06 21:26 ` Thomas Gleixner
2022-05-13 19:01 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 13/29] iommu/amd: Compose MSI messages for NMI irqs in non-IR format Ricardo Neri
2022-05-06 21:31 ` Thomas Gleixner
2022-05-13 19:03 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 14/29] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 15/29] x86/hpet: Add helper function hpet_set_comparator_periodic() Ricardo Neri
2022-05-06 21:41 ` Thomas Gleixner
2022-05-06 21:51 ` Thomas Gleixner
2022-05-13 21:29 ` Ricardo Neri
2022-05-13 21:19 ` Ricardo Neri
2022-05-14 8:17 ` Thomas Gleixner
2022-05-17 22:54 ` Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 16/29] x86/hpet: Prepare IRQ assignments to use the X86_ALLOC_AS_NMI flag Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 17/29] x86/hpet: Reserve an HPET channel for the hardlockup detector Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 18/29] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 19/29] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2022-05-05 23:59 ` [PATCH v6 20/29] init/main: Delay initialization of the lockup detector after smp_init() Ricardo Neri
2022-05-10 10:38 ` Nicholas Piggin
2022-05-13 23:16 ` Ricardo Neri
2022-05-20 0:25 ` Nicholas Piggin
2022-05-06 0:00 ` [PATCH v6 21/29] x86/nmi: Add an NMI_WATCHDOG NMI handler category Ricardo Neri
2022-05-09 13:59 ` Thomas Gleixner
2022-05-17 18:41 ` Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 22/29] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2022-05-09 14:03 ` Thomas Gleixner
2022-05-13 22:16 ` Ricardo Neri
2022-05-14 14:04 ` Thomas Gleixner
2022-05-06 0:00 ` [PATCH v6 23/29] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 24/29] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2022-05-10 10:46 ` Nicholas Piggin
2022-05-13 23:17 ` Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 25/29] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 26/29] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 27/29] watchdog: Expose lockup_detector_reconfigure() Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 28/29] x86/tsc: Restart NMI watchdog after refining tsc_khz Ricardo Neri
2022-05-10 11:16 ` Nicholas Piggin
2022-05-10 11:44 ` Thomas Gleixner
2022-05-17 22:53 ` Ricardo Neri
2022-05-17 22:08 ` Ricardo Neri
2022-05-06 0:00 ` [PATCH v6 29/29] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
2022-05-10 12:14 ` Nicholas Piggin
2022-05-17 3:09 ` Ricardo Neri
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