Re: [PATCH 04/16] libnvdimm: Move nd_numa_attribute_group to device_type

[Aneesh Kumar K.V]

On 11/13/19 6:56 AM, Dan Williams wrote:
> On Tue, Nov 12, 2019 at 1:23 AM Aneesh Kumar K.V
> <aneesh.kumar@xxxxxxxxxxxxx> wrote:
> > Dan Williams <dan.j.williams@xxxxxxxxx> writes:
> >
> > > A 'struct device_type' instance can carry default attributes for the
> > > device. Use this facility to remove the export of
> > > nd_numa_attribute_group and put the responsibility on the core rather
> > > than leaf implementations to define this attribute.
> > >
> > > Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
> > > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > > Cc: "Oliver O'Halloran" <oohall@xxxxxxxxx>
> > > Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> > > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> > > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> >
> >
> > can we also expose target_node in a similar way? This allows application
> > to better understand the node locality of the SCM device.
>
> It is already exported for device-dax instances. See
> DEVICE_ATTR_RO(target_node) in drivers/dax/bus.c. I did not see a use
> case for it to be exported for other nvdimm device types.

some applications do want to access the fsdax namspace as different 
mount points based on numa affinity. If can differentiate the two 
regions with different target_node and same numa_node, that will help 
them better isolate these mounts.

-aneesh