From: Thomas Gleixner <tglx@linutronix.de>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ming Lei <ming.lei@redhat.com>, 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>,
Sumit Saxena <sumit.saxena@broadcom.com>,
Kashyap Desai <kashyap.desai@broadcom.com>,
Shivasharan Srikanteshwara
<shivasharan.srikanteshwara@broadcom.com>
Subject: Re: [patch V5 4/8] nvme-pci: Simplify interrupt allocation
Date: Fri, 15 Feb 2019 10:52:51 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.21.1902151051470.1646@nanos.tec.linutronix.de> (raw)
In-Reply-To: <868syhs8tn.wl-marc.zyngier@arm.com>
On Fri, 15 Feb 2019, Marc Zyngier wrote:
> On Thu, 14 Feb 2019 20:47:59 +0000,
> Thomas Gleixner <tglx@linutronix.de> wrote:
> > drivers/nvme/host/pci.c | 108 ++++++++++++------------------------------------
> > 1 file changed, 28 insertions(+), 80 deletions(-)
> >
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -2041,41 +2041,32 @@ static int nvme_setup_host_mem(struct nv
> > return ret;
> > }
> >
> > -/* irq_queues covers admin queue */
> > -static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues)
> > +/*
> > + * nirqs is the number of interrupts available for write and read
> > + * queues. The core already reserved an interrupt for the admin queue.
> > + */
> > +static void nvme_calc_irq_sets(struct irq_affinity *affd, unsigned int nrirqs)
> > {
> > - unsigned int this_w_queues = write_queues;
> > -
> > - WARN_ON(!irq_queues);
> > -
> > - /*
> > - * Setup read/write queue split, assign admin queue one independent
> > - * irq vector if irq_queues is > 1.
> > - */
> > - if (irq_queues <= 2) {
> > - dev->io_queues[HCTX_TYPE_DEFAULT] = 1;
> > - dev->io_queues[HCTX_TYPE_READ] = 0;
> > - return;
> > - }
> > + struct nvme_dev *dev = affd->priv;
> > + unsigned int nr_read_queues;
> >
> > /*
> > - * If 'write_queues' is set, ensure it leaves room for at least
> > - * one read queue and one admin queue
> > - */
> > - if (this_w_queues >= irq_queues)
> > - this_w_queues = irq_queues - 2;
> > -
> > - /*
> > - * If 'write_queues' is set to zero, reads and writes will share
> > - * a queue set.
> > - */
> > - if (!this_w_queues) {
> > - dev->io_queues[HCTX_TYPE_DEFAULT] = irq_queues - 1;
> > - dev->io_queues[HCTX_TYPE_READ] = 0;
> > - } else {
> > - dev->io_queues[HCTX_TYPE_DEFAULT] = this_w_queues;
> > - dev->io_queues[HCTX_TYPE_READ] = irq_queues - this_w_queues - 1;
> > - }
> > + * If only one interrupt is available, combine write and read
> > + * queues. If 'write_queues' is set, ensure it leaves room for at
> > + * least one read queue.
>
> [Full disclaimer: I only have had two coffees this morning, and it is
> only at the fourth that my brain is able to kick in...]
>
> I don't know much about NVME, but I feel like there is a small
> disconnect between the code and the above comment, which says "leave
> room for at least one read queue"...
>
> > + */
> > + if (nrirqs == 1)
> > + nr_read_queues = 0;
> > + else if (write_queues >= nrirqs)
> > + nr_read_queues = nrirqs - 1;
>
> ... while this seem to ensure that we carve out one write queue out of
> the irq set. It looks like a departure from the original code, which
> would set nr_read_queues to 1 in that particular case.
Bah. right you are.
next prev parent reply other threads:[~2019-02-15 9:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 20:47 [patch V5 0/8] genirq/affinity: Overhaul the multiple interrupt sets support Thomas Gleixner
2019-02-14 20:47 ` [patch V5 1/8] genirq/affinity: Code consolidation Thomas Gleixner
2019-02-14 20:47 ` [patch V5 2/8] genirq/affinity: Store interrupt sets size in struct irq_affinity Thomas Gleixner
2019-02-14 20:47 ` [patch V5 3/8] genirq/affinity: Add new callback for (re)calculating interrupt sets Thomas Gleixner
2019-02-14 20:47 ` [patch V5 4/8] nvme-pci: Simplify interrupt allocation Thomas Gleixner
2019-02-14 22:41 ` Ming Lei
2019-02-14 23:55 ` Thomas Gleixner
2019-02-15 23:00 ` Thomas Gleixner
2019-02-15 9:24 ` Marc Zyngier
2019-02-15 9:52 ` Thomas Gleixner [this message]
2019-02-15 9:54 ` Thomas Gleixner
2019-02-14 20:48 ` [patch V5 5/8] genirq/affinity: Remove the leftovers of the original set support Thomas Gleixner
2019-02-14 20:48 ` [patch V5 6/8] PCI/MSI: Remove obsolete sanity checks for multiple interrupt sets Thomas Gleixner
2019-02-14 20:48 ` [patch V5 7/8] genirq/affinity: Set is_managed in the spreading function Thomas Gleixner
2019-02-14 20:48 ` [patch V5 8/8] genirq/affinity: Add support for non-managed affinity sets Thomas Gleixner
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