Re: [PATCH v12 06/13] nvme-pci: use block layer helpers to constrain queue affinity

[Aaron Tomlin]

On Wed, Apr 22, 2026 at 02:52:08PM -0400, Aaron Tomlin wrote:
> From: Daniel Wagner <wagi@xxxxxxxxxx>
> 
> Ensure that IRQ affinity setup also respects the queue-to-CPU mapping
> constraints provided by the block layer. This allows the NVMe driver
> to avoid assigning interrupts to CPUs that the block layer has excluded
> (e.g., isolated CPUs).
> 
> Signed-off-by: Daniel Wagner <wagi@xxxxxxxxxx>
> Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
> Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
> Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxxx>
> ---
>  drivers/nvme/host/pci.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index db5fc9bf6627..daa041d15d3c 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2862,6 +2862,7 @@ static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues)
>  		.pre_vectors	= 1,
>  		.calc_sets	= nvme_calc_irq_sets,
>  		.priv		= dev,
> +		.mask		= blk_mq_possible_queue_affinity(),
>  	};
>  	unsigned int irq_queues, poll_queues;
>  	unsigned int flags = PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY;
> -- 
> 2.51.0

Hi Daniel, Martin, Hannes,

I think we can drop this patch, including other similar changes [1][2].

The next iteration of patch 12 [3] in my queue, irq_create_affinity_masks()
has been modified to respect the housekeeping CPU mask. By intersecting the
base affinity mask with the HK_TYPE_IO_QUEUE mask prior to topological
distribution (group_mask_cpus_evenly()), we ensure that managed interrupts
are kept off isolated CPUs.

[1]: https://lore.kernel.org/lkml/20260422185215.100929-8-atomlin@xxxxxxxxxxx/
[2]: https://lore.kernel.org/lkml/20260422185215.100929-9-atomlin@xxxxxxxxxxx/
[3]: https://lore.kernel.org/lkml/20260422185215.100929-13-atomlin@xxxxxxxxxxx/

-- 
Aaron Tomlin

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