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SubjectRe: [PATCHv4 05/13] Documentation/ABI: Add new node sysfs attributes
On Fri, Jan 18, 2019 at 3:22 AM Jonathan Cameron
<jonathan.cameron@huawei.com> wrote:
>
> On Wed, 16 Jan 2019 10:57:56 -0700
> Keith Busch <keith.busch@intel.com> wrote:
>
> > Add entries for memory initiator and target node class attributes.
> >
> > Signed-off-by: Keith Busch <keith.busch@intel.com>
> > ---
> > Documentation/ABI/stable/sysfs-devices-node | 25 ++++++++++++++++++++++++-
> > 1 file changed, 24 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node
> > index 3e90e1f3bf0a..a9c47b4b0eee 100644
> > --- a/Documentation/ABI/stable/sysfs-devices-node
> > +++ b/Documentation/ABI/stable/sysfs-devices-node
> > @@ -90,4 +90,27 @@ Date: December 2009
> > Contact: Lee Schermerhorn <lee.schermerhorn@hp.com>
> > Description:
> > The node's huge page size control/query attributes.
> > - See Documentation/admin-guide/mm/hugetlbpage.rst
> > \ No newline at end of file
> > + See Documentation/admin-guide/mm/hugetlbpage.rst
> > +
> > +What: /sys/devices/system/node/nodeX/classY/
> > +Date: December 2018
> > +Contact: Keith Busch <keith.busch@intel.com>
> > +Description:
> > + The node's relationship to other nodes for access class "Y".
> > +
> > +What: /sys/devices/system/node/nodeX/classY/initiator_nodelist
> > +Date: December 2018
> > +Contact: Keith Busch <keith.busch@intel.com>
> > +Description:
> > + The node list of memory initiators that have class "Y" access
> > + to this node's memory. CPUs and other memory initiators in
> > + nodes not in the list accessing this node's memory may have
> > + different performance.
> > +
> > +What: /sys/devices/system/node/nodeX/classY/target_nodelist
> > +Date: December 2018
> > +Contact: Keith Busch <keith.busch@intel.com>
> > +Description:
> > + The node list of memory targets that this initiator node has
> > + class "Y" access. Memory accesses from this node to nodes not
> > + in this list may have differet performance.
>
> Different performance from what? In the other thread we established that
> these target_nodelists are kind of a backwards reference, they all have
> their characteristics anyway. Perhaps this just needs to say:
> "Memory access from this node to these targets may have different performance"?
>
> i.e. Don't make the assumption I did that they should all be the same!

I think a clarification of "class" is needed in this context. A
"class" is the the set of initiators that have the same rated
performance to a given target set. In other words "class" is a tuple
of (performance profile, initiator set, target set). Different
performance creates a different tuple / class.

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