[PATCH v2 2/2] nvme-pci: take the io_queue_number into account when setting number of io queues

[ming.lei@redhat.com (Ming Lei)]

On Mon, Dec 24, 2018@12:12:19PM +0800, Shan Hai wrote:
> Add a wrapper around num_possible_cpus() to take the new added module
> parameter account when setting number of io queues.
> 
> Signed-off-by: Shan Hai <shan.hai at oracle.com>
> ---
>  drivers/nvme/host/pci.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 0d60451..e359e90 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -219,6 +219,11 @@ struct nvme_iod {
>  	struct scatterlist inline_sg[0];
>  };
>  
> +static inline unsigned int nvme_io_queue_number(void)
> +{
> +	return min_t(unsigned int, io_queue_number, num_possible_cpus());
> +}
> +
>  /*
>   * Check we didin't inadvertently grow the command struct
>   */
> @@ -241,7 +246,7 @@ static inline void _nvme_check_size(void)
>  
>  static inline unsigned int nvme_dbbuf_size(u32 stride)
>  {
> -	return ((num_possible_cpus() + 1) * 8 * stride);
> +	return ((nvme_io_queue_number() + 1) * 8 * stride);
>  }
>  
>  static int nvme_dbbuf_dma_alloc(struct nvme_dev *dev)
> @@ -1923,7 +1928,7 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
>  		.pre_vectors = 1
>  	};
>  
> -	nr_io_queues = num_possible_cpus();
> +	nr_io_queues = nvme_io_queue_number();
>  	result = nvme_set_queue_count(&dev->ctrl, &nr_io_queues);
>  	if (result < 0)
>  		return result;
> @@ -2512,7 +2517,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (!dev)
>  		return -ENOMEM;
>  
> -	dev->queues = kcalloc_node(num_possible_cpus() + 1,
> +	dev->queues = kcalloc_node(nvme_io_queue_number() + 1,
>  			sizeof(struct nvme_queue), GFP_KERNEL, node);
>  	if (!dev->queues)
>  		goto free;
> -- 
> 2.7.4

You need to make the patch against block/for-4.21, or the latest linus
tree after Linus pulls in block/for-4.21, so far not done yet.

Especially max_queue_count() and max_io_queues() are introduced, and
looks you just need to change max_io_queues().

So please fold the two into one patch, and the shape may be something
like the following:

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index d839bbe408c3..a2d1da6ca6c0 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -81,6 +81,12 @@ static const struct kernel_param_ops queue_count_ops = {
 	.get = param_get_int,
 };
 
+static int default_queues;
+module_param_cb(default_queues, &queue_count_ops, &default_queues, 0644);
+MODULE_PARM_DESC(default_queues,
+	"Number of queues to use DEFAULT queue type. If not set, "
+	"num_possible_cpus() will be used.");
+
 static int write_queues;
 module_param_cb(write_queues, &queue_count_ops, &write_queues, 0644);
 MODULE_PARM_DESC(write_queues,
@@ -254,7 +260,9 @@ static inline void _nvme_check_size(void)
 
 static unsigned int max_io_queues(void)
 {
-	return num_possible_cpus() + write_queues + poll_queues;
+	int def_io_queues = default_queues ?: num_possible_cpus();
+
+	return def_io_queues + write_queues + poll_queues;
 }
 
 static unsigned int max_queue_count(void)

Thanks,
Ming