From: Ming Lei <ming.lei@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
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 21:45:23 +0800 [thread overview]
Message-ID: <20190217134522.GH7296@ming.t460p> (raw)
In-Reply-To: <20190216172228.869750763@linutronix.de>
Hi Thomas,
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?
>
> Add a bitmap to struct irq_affinity which allows the driver to mark a
> particular set of interrupts as non managed. Check the bitmap during
> spreading and use the result to mark the interrupts in the sets
> accordingly.
>
> The unmanaged interrupts get initial spreading, but user space can change
> their affinity later on. For the managed sets, i.e. the corresponding bit
> in the mask is not set, there is no change in behaviour.
>
> Usage example:
>
> struct irq_affinity affd = {
> .pre_vectors = 2,
> .unmanaged_sets = 0x02,
> .calc_sets = drv_calc_sets,
> };
> ....
>
> 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?
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.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> include/linux/interrupt.h | 2 ++
> kernel/irq/affinity.c | 16 +++++++++++-----
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> Index: b/include/linux/interrupt.h
> ===================================================================
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -251,6 +251,7 @@ struct irq_affinity_notify {
> * the MSI(-X) vector space
> * @nr_sets: The number of interrupt sets for which affinity
> * spreading is required
> + * @unmanaged_sets: Bitmap to mark entries in the @set_size array unmanaged
> * @set_size: Array holding the size of each interrupt set
> * @calc_sets: Callback for calculating the number and size
> * of interrupt sets
> @@ -261,6 +262,7 @@ struct irq_affinity {
> unsigned int pre_vectors;
> unsigned int post_vectors;
> unsigned int nr_sets;
> + unsigned int unmanaged_sets;
> unsigned int set_size[IRQ_AFFINITY_MAX_SETS];
> void (*calc_sets)(struct irq_affinity *, unsigned int nvecs);
> void *priv;
> Index: b/kernel/irq/affinity.c
> ===================================================================
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -249,6 +249,8 @@ irq_create_affinity_masks(unsigned int n
> unsigned int affvecs, curvec, usedvecs, i;
> struct irq_affinity_desc *masks = NULL;
>
> + BUILD_BUG_ON(IRQ_AFFINITY_MAX_SETS > sizeof(affd->unmanaged_sets) * 8);
> +
> /*
> * Determine the number of vectors which need interrupt affinities
> * assigned. If the pre/post request exhausts the available vectors
> @@ -292,7 +294,8 @@ irq_create_affinity_masks(unsigned int n
> * have multiple sets, build each sets affinity mask separately.
> */
> 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.
Thanks,
Ming
next prev parent reply other threads:[~2019-02-17 13:45 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 [this message]
2019-02-17 19:17 ` Thomas Gleixner
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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