linux-kernel - Re: [PATCH V3] nvme-pci: assign separate irq vectors for adminq and ioq1

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Message-ID: <20180313104452.GA8782@ming.t460p>
Date:   Tue, 13 Mar 2018 18:45:00 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jianchao Wang <jianchao.w.wang@...cle.com>
Cc:     keith.busch@...el.com, axboe@...com, hch@....de, sagi@...mberg.me,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] nvme-pci: assign separate irq vectors for adminq and
 ioq1

On Tue, Mar 13, 2018 at 05:58:08PM +0800, Jianchao Wang wrote:
> Currently, adminq and ioq1 share the same irq vector which is set
> affinity to cpu0. If a system allows cpu0 to be offlined, the adminq
> will not be able work any more.
> 
> To fix this, assign separate irq vectors for adminq and ioq1. Set
> .pre_vectors == 1 when allocate irq vectors, then assign the first
> one to adminq which will have affinity cpumask with all possible
> cpus. On the other hand, if controller has only legacy or single
> -message MSI, we will setup adminq and 1 ioq and let them share
> the only one irq vector.
> 
> Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
> ---
> V2->V3
>  - change changelog based on Ming's insights
>  - some cleanup based on Andy's suggestions
> 
> V1->V2
>  - add case to handle the scenario where there is only one irq
>    vector
>  - add nvme_ioq_vector to map ioq vector and qid
> 
>  drivers/nvme/host/pci.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index b6f43b7..47c33f4 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -84,6 +84,7 @@ struct nvme_dev {
>  	struct dma_pool *prp_small_pool;
>  	unsigned online_queues;
>  	unsigned max_qid;
> +	unsigned int num_vecs;
>  	int q_depth;
>  	u32 db_stride;
>  	void __iomem *bar;
> @@ -139,6 +140,17 @@ static inline struct nvme_dev *to_nvme_dev(struct nvme_ctrl *ctrl)
>  	return container_of(ctrl, struct nvme_dev, ctrl);
>  }
>  
> +static inline unsigned int nvme_ioq_vector(struct nvme_dev *dev,
> +		unsigned int qid)
> +{
> +	/*
> +	 * If controller has only legacy or single-message MSI, there will
> +	 * be only 1 irq vector. At the moment, we setup adminq + 1 ioq
> +	 * and let them share irq vector.
> +	 */
> +	return (dev->num_vecs == 1) ? 0 : qid;
> +}
> +
>  /*
>   * An NVM Express queue.  Each device has at least two (one for admin
>   * commands and one for I/O commands).
> @@ -1457,7 +1469,7 @@ static int nvme_create_queue(struct nvme_queue *nvmeq, int qid)
>  		nvmeq->sq_cmds_io = dev->cmb + offset;
>  	}
>  
> -	nvmeq->cq_vector = qid - 1;
> +	nvmeq->cq_vector = nvme_ioq_vector(dev, qid);
>  	result = adapter_alloc_cq(dev, qid, nvmeq);
>  	if (result < 0)
>  		goto release_vector;
> @@ -1628,11 +1640,12 @@ static int nvme_create_io_queues(struct nvme_dev *dev)
>  {
>  	unsigned i, max;
>  	int ret = 0;
> +	int vec;
>  
>  	for (i = dev->ctrl.queue_count; i <= dev->max_qid; i++) {
> -		/* vector == qid - 1, match nvme_create_queue */
> +		vec = nvme_ioq_vector(dev, i);
>  		if (nvme_alloc_queue(dev, i, dev->q_depth,
> -		     pci_irq_get_node(to_pci_dev(dev->dev), i - 1))) {
> +		     pci_irq_get_node(to_pci_dev(dev->dev), vec))) {
>  			ret = -ENOMEM;
>  			break;
>  		}
> @@ -1913,6 +1926,8 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
>  	struct pci_dev *pdev = to_pci_dev(dev->dev);
>  	int result, nr_io_queues;
>  	unsigned long size;
> +	struct irq_affinity affd = {.pre_vectors = 1};
> +	int ret;
>  
>  	nr_io_queues = num_possible_cpus();
>  	result = nvme_set_queue_count(&dev->ctrl, &nr_io_queues);
> @@ -1949,11 +1964,12 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
>  	 * setting up the full range we need.
>  	 */
>  	pci_free_irq_vectors(pdev);
> -	nr_io_queues = pci_alloc_irq_vectors(pdev, 1, nr_io_queues,
> -			PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY);
> -	if (nr_io_queues <= 0)
> +	ret = pci_alloc_irq_vectors_affinity(pdev, 1, (nr_io_queues + 1),
> +			PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
> +	if (ret <= 0)
>  		return -EIO;
> -	dev->max_qid = nr_io_queues;
> +	dev->num_vecs = ret;
> +	dev->max_qid = max(ret - 1, 1);
>  
>  	/*
>  	 * Should investigate if there's a performance win from allocating
> -- 
> 2.7.4
> 

Reviewed-by: Ming Lei <ming.lei@...hat.com>

Thanks,
Ming