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From: Thomas Gleixner <tglx@linutronix.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	Bjorn Helgaas <helgaas@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org,
	Keith Busch <keith.busch@intel.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Sumit Saxena <sumit.saxena@broadcom.com>,
	Kashyap Desai <kashyap.desai@broadcom.com>,
	Shivasharan Srikanteshwara 
	<shivasharan.srikanteshwara@broadcom.com>
Subject: Re: [patch v6 7/7] genirq/affinity: Add support for non-managed affinity sets
Date: Sun, 17 Feb 2019 20:17:05 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.21.1902172010060.1683@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190217134522.GH7296@ming.t460p>

On Sun, 17 Feb 2019, Ming Lei wrote:
> On Sat, Feb 16, 2019 at 06:13:13PM +0100, Thomas Gleixner wrote:
> > Some drivers need an extra set of interrupts which should not be marked
> > managed, but should get initial interrupt spreading.
> 
> Could you share the drivers and their use case?

You were Cc'ed on that old discussion:

 https://lkml.kernel.org/r/300d6fef733ca76ced581f8c6304bac6@mail.gmail.com

> > For both interrupt sets the interrupts are properly spread out, but the
> > second set is not marked managed.
> 
> Given drivers only care the managed vs non-managed interrupt numbers,
> just wondering why this case can't be covered by .pre_vectors &
> .post_vectors?

Well, yes, but post/pre are not subject to spreading and I really don't
want to go there.

> Also this kind of usage may break blk-mq easily, in which the following
> rule needs to be respected:
> 
> 1) all CPUs are required to spread among each interrupt set
> 
> 2) no any CPU is shared between two IRQs in same set.

I don't see how that would break blk-mq. The unmanaged set is not used by
the blk-mq stuff, that's some driver internal voodoo. So blk-mq still gets
a perfectly spread and managed interrupt set for the queues.

> >  	for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
> > -		unsigned int this_vecs = affd->set_size[i];
> > +		bool managed = affd->unmanaged_sets & (1U << i) ? true : false;
> 
> The above check is inverted.

Doh. Stupid me.

Thanks,

	tglx

  reply	other threads:[~2019-02-17 19:17 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-16 17:13 [patch v6 0/7] genirq/affinity: Overhaul the multiple interrupt sets support Thomas Gleixner
2019-02-16 17:13 ` [patch v6 1/7] genirq/affinity: Code consolidation Thomas Gleixner
2019-02-17 13:36   ` Ming Lei
2019-02-16 17:13 ` [patch v6 2/7] genirq/affinity: Store interrupt sets size in struct irq_affinity Thomas Gleixner
2019-02-16 17:13 ` [patch v6 3/7] genirq/affinity: Add new callback for (re)calculating interrupt sets Thomas Gleixner
2021-06-15 19:57   ` Bjorn Helgaas
2021-06-15 20:04     ` Christoph Hellwig
2021-06-16  0:40     ` Ming Lei
2021-06-18 19:32       ` Thomas Gleixner
2021-06-18 19:19     ` Thomas Gleixner
2019-02-16 17:13 ` [patch v6 4/7] nvme-pci: Simplify interrupt allocation Thomas Gleixner
2019-02-16 17:13 ` [patch v6 5/7] genirq/affinity: Remove the leftovers of the original set support Thomas Gleixner
2019-02-17 13:39   ` Ming Lei
2019-02-16 17:13 ` [patch v6 6/7] PCI/MSI: Remove obsolete sanity checks for multiple interrupt sets Thomas Gleixner
2019-02-17 13:39   ` Ming Lei
2019-02-16 17:13 ` [patch v6 7/7] genirq/affinity: Add support for non-managed affinity sets Thomas Gleixner
2019-02-17 13:45   ` Ming Lei
2019-02-17 19:17     ` Thomas Gleixner [this message]
2019-02-18  2:49       ` Ming Lei
2019-02-18  7:25         ` Thomas Gleixner
2019-02-18  8:43 ` [patch v6 0/7] genirq/affinity: Overhaul the multiple interrupt sets support Marc Zyngier

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