Re: [PATCH v2 13/18] libnvdimm: Export the target_node attribute for regions and namespaces

Aneesh Kumar K.V
2019-11-18T09:45:35Z

Dan Williams <dan.j.williams@intel.com> writes:

> Aneesh points out that some platforms may have "local" attached
> persistent memory and "remote" persistent memory that map to the same
> "online" node, or persistent memory devices with different performance
> properties. In this case 'numa_node' is identical for the two instances,
> but 'target_node' is differentiated so platform firmware can communicate
> distinct performance properties per range. Expose 'target_node' by
> default to allow for disambiguation of devices that share the same
> numa_map_to_online_node() result.
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> Reported-by: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> drivers/nvdimm/bus.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
> index 1d330d46d036..f76d709426f7 100644
> --- a/drivers/nvdimm/bus.c
> +++ b/drivers/nvdimm/bus.c
> @@ -685,17 +685,46 @@ static ssize_t numa_node_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(numa_node);
>
> +static int nvdimm_dev_to_target_node(struct device *dev)
> +{
> + struct device *parent = dev->parent;
> + struct nd_region *nd_region = NULL;
> +
> + if (is_nd_region(dev))
> + nd_region = to_nd_region(dev);
> + else if (parent && is_nd_region(parent))
> + nd_region = to_nd_region(parent);
> +
> + if (!nd_region)
> + return NUMA_NO_NODE;
> + return nd_region->target_node;
> +}
> +
> +static ssize_t target_node_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", nvdimm_dev_to_target_node(dev));
> +}
> +static DEVICE_ATTR_RO(target_node);
> +
> static struct attribute *nd_numa_attributes[] = {
> &dev_attr_numa_node.attr,
> + &dev_attr_target_node.attr,
> NULL,
> };
>
> static umode_t nd_numa_attr_visible(struct kobject *kobj, struct attribute *a,
> int n)
> {
> + struct device *dev = container_of(kobj, typeof(*dev), kobj);
> +
> if (!IS_ENABLED(CONFIG_NUMA))
> return 0;
>
> + if (a == &dev_attr_target_node.attr &&
> + nvdimm_dev_to_target_node(dev) == NUMA_NO_NODE)
> + return 0;
> +
> return a->mode;
> }
>