linux-kernel - Re: [PATCH v3 3/3] libnvdimm: Add sysfs numa

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Date:	Wed, 24 Jun 2015 10:38:46 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] libnvdimm: Add sysfs numa_node to NVDIMM devices

On Tue, 2015-06-23 at 17:26 -0700, Dan Williams wrote:
> On Fri, Jun 19, 2015 at 11:18 AM, Toshi Kani <toshi.kani@...com> wrote:
> > Add support of sysfs 'numa_node' to I/O-related NVDIMM devices
> > under /sys/bus/nd/devices, regionN, namespaceN.0, and bttN.
> > When bttN is not set up, its numa_node returns -1 (NUMA_NO_NODE).
> >
> > An example of numa_node values on a 2-socket system with a single
> > NVDIMM range on each socket is shown below.
> >   /sys/bus/nd/devices
> >   |-- btt0/numa_node:-1
> >   |-- btt1/numa_node:0
> >   |-- namespace0.0/numa_node:0
> >   |-- namespace1.0/numa_node:1
> >   |-- region0/numa_node:0
> >   |-- region1/numa_node:1
> >
> > These numa_node files are then linked under the block class of
> > their device names.
> >   /sys/class/block/pmem0/device/numa_node:0
> >   /sys/class/block/pmem0s/device/numa_node:0
> >   /sys/class/block/pmem1/device/numa_node:1
> >
> > This enables numactl(8) to accept 'block:' and 'file:' paths of
> > pmem and btt devices as shown in the examples below.
> >   numactl --preferred block:pmem0 --show
> >   numactl --preferred file:/dev/pmem0s --show
> >
> > Signed-off-by: Toshi Kani <toshi.kani@...com>
> > ---
> >  drivers/acpi/nfit.c             |    1 +
> >  drivers/nvdimm/btt_devs.c       |    1 +
> >  drivers/nvdimm/bus.c            |   30 ++++++++++++++++++++++++++++++
> >  drivers/nvdimm/namespace_devs.c |    1 +
> >  include/linux/libnvdimm.h       |    1 +
> >  5 files changed, 34 insertions(+)
> >
> > diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
> > index 5997753..9cb63ac 100644
> > --- a/drivers/acpi/nfit.c
> > +++ b/drivers/acpi/nfit.c
> > @@ -873,6 +873,7 @@ static const struct attribute_group *acpi_nfit_region_attribute_groups[] = {
> >         &nd_region_attribute_group,
> >         &nd_mapping_attribute_group,
> >         &nd_device_attribute_group,
> > +       &nd_numa_attribute_group,
> >         &acpi_nfit_region_attribute_group,
> >         NULL,
> >  };
> > diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> > index bcf77dc..a7b192f 100644
> > --- a/drivers/nvdimm/btt_devs.c
> > +++ b/drivers/nvdimm/btt_devs.c
> > @@ -308,6 +308,7 @@ static struct attribute_group nd_btt_attribute_group = {
> >  static const struct attribute_group *nd_btt_attribute_groups[] = {
> >         &nd_btt_attribute_group,
> >         &nd_device_attribute_group,
> > +       &nd_numa_attribute_group,
> >         NULL,
> >  };
> >
> > diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
> > index 67525f9..03c0ee1 100644
> > --- a/drivers/nvdimm/bus.c
> > +++ b/drivers/nvdimm/bus.c
> > @@ -420,6 +420,36 @@ struct attribute_group nd_device_attribute_group = {
> >  };
> >  EXPORT_SYMBOL_GPL(nd_device_attribute_group);
> >
> > +static ssize_t numa_node_show(struct device *dev,
> > +               struct device_attribute *attr, char *buf)
> > +{
> > +       return sprintf(buf, "%d\n", dev_to_node(dev));
> > +}
> 
> So patch 2 collided with the requested BTT stacking rework and
> prompted me to take a closer look.  Shouldn't numa_node_show() be
> changed like this?

numa_node_show() is listed in its own nd_numa_attribute_group for using
is_visible.  This nd_numa_attribute_group is then listed by region
(acpi_nfit_region_attribute_groups), namespace
(nd_namespace_attribute_groups), and btt (nd_btt_attribute_groups).
Therefore, numa_node_show() is only called with these device objects.
So, I do not think we need such change.  Or are you suggesting to change
the way attribute group is set? 

Thanks,
-Toshi


> @@ -273,7 +273,12 @@ EXPORT_SYMBOL_GPL(nd_device_attribute_group);
>  static ssize_t numa_node_show(struct device *dev,
>                 struct device_attribute *attr, char *buf)
>  {
> -       return sprintf(buf, "%d\n", dev_to_node(dev));
> +       if (is_nd_region(dev))
> +               return sprintf(buf, "%d\n", dev_to_node(dev));
> +       else if (is_nd_region(dev->parent))
> +               return sprintf(buf, "%d\n", dev_to_node(dev->parent));
> +       else
> +               return sprintf(buf, "-1\n");
>  }
>  static DEVICE_ATTR_RO(numa_node);



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