Re: [PATCH v3 03/15] blk-mq: introduce blk_mq_dev_map_queues

Christoph Hellwig
2024-08-06T13:26:48Z

On Tue, Aug 06, 2024 at 02:06:35PM +0200, Daniel Wagner wrote:
> From: Ming Lei <ming.lei@redhat.com>
>
> blk_mq_pci_map_queues and blk_mq_virtio_map_queues will create a CPU to
> hardware queue mapping based on affinity information. These two
> function share code which only differs on how the affinity information
> is retrieved. Also there is the hisi_sas which open codes the same loop.
>
> Thus introduce a new helper function for creating these mappings which
> takes an callback function for fetching the affinity mask. Also
> introduce common helper function for PCI and virtio devices to retrieve
> affinity masks.
>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> [dwagner: - removed fallback mapping
> - added affintity helpers
> - updated commit message]
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> block/blk-mq-cpumap.c | 35 +++++++++++++++++++++++++++++++++++
> block/blk-mq-pci.c | 18 ++++++++++++++++++
> block/blk-mq-virtio.c | 19 +++++++++++++++++++
> include/linux/blk-mq-pci.h | 2 ++
> include/linux/blk-mq-virtio.h | 3 +++
> include/linux/blk-mq.h | 5 +++++
> 6 files changed, 82 insertions(+)
>
> diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
> index 9638b25fd521..7037a2dc485f 100644
> --- a/block/blk-mq-cpumap.c
> +++ b/block/blk-mq-cpumap.c
> @@ -54,3 +54,38 @@ int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index)
>
> return NUMA_NO_NODE;
> }
> +
> +/**
> + * blk_mq_dev_map_queues - Create CPU to hardware queue mapping
> + * @qmap: CPU to hardware queue map.
> + * @dev_off: Offset to use for the device.
> + * @dev_data: Device data passed to get_queue_affinity().
> + * @get_queue_affinity: Callback to retrieve queue affinity.
> + *
> + * Create a CPU to hardware queue mapping in @qmap. For each queue
> + * @get_queue_affinity will be called to retrieve the affinity for given
> + * queue.
> + */
> +void blk_mq_dev_map_queues(struct blk_mq_queue_map *qmap,
> + void *dev_data, int dev_off,
> + get_queue_affinty_fn *get_queue_affinity)
> +{
> + const struct cpumask *mask;
> + unsigned int queue, cpu;
> +
> + for (queue = 0; queue < qmap->nr_queues; queue++) {
> + mask = get_queue_affinity(dev_data, dev_off, queue);
> + if (!mask)
> + goto fallback;
> +
> + for_each_cpu(cpu, mask)
> + qmap->mq_map[cpu] = qmap->queue_offset + queue;
> + }
> +
> + return;
> +
> +fallback:
> + WARN_ON_ONCE(qmap->nr_queues > 1);
> + blk_mq_clear_mq_map(qmap);
> +}
> +EXPORT_SYMBOL_GPL(blk_mq_dev_map_queues);
> diff --git a/block/blk-mq-pci.c b/block/blk-mq-pci.c
> index d47b5c73c9eb..71a73238aeb2 100644
> --- a/block/blk-mq-pci.c
> +++ b/block/blk-mq-pci.c
> @@ -44,3 +44,21 @@ void blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
> blk_mq_clear_mq_map(qmap);
> }
> EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
> +
> +/**
> + * blk_mq_pci_get_queue_affinity - get affinity mask queue mapping for PCI device
> + * @dev_data: Pointer to struct pci_dev.
> + * @offset: Offset to use for the pci irq vector
> + * @queue: Queue index
> + *
> + * This function returns for a queue the affinity mask for a PCI device.
> + * It is usually used as callback for blk_mq_dev_map_queues().
> + */
> +const struct cpumask *blk_mq_pci_get_queue_affinity(void *dev_data, int offset,
> + int queue)
> +{
> + struct pci_dev *pdev = dev_data;
> +
> + return pci_irq_get_affinity(pdev, offset + queue);
> +}
> +EXPORT_SYMBOL_GPL(blk_mq_pci_get_queue_affinity);
> diff --git a/block/blk-mq-virtio.c b/block/blk-mq-virtio.c
> index 68d0945c0b08..d3d33f8d69ce 100644
> --- a/block/blk-mq-virtio.c
> +++ b/block/blk-mq-virtio.c
> @@ -44,3 +44,22 @@ void blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap,
> blk_mq_map_queues(qmap);
> }
> EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);
> +
> +/**
> + * blk_mq_virtio_get_queue_affinity - get affinity mask queue mapping for virtio device

Please avoid the overly long line here.

> +const struct cpumask *blk_mq_virtio_get_queue_affinity(void *dev_data,
> + int offset,
> + int queue)
> +{

And maybe use sane formatting here:

const struct cpumask *blk_mq_virtio_get_queue_affinity(void *dev_data,
int offset, int queue)

/me also wonders why the parameters aren't unsigned, but that's history..