On Fri, Feb 09, 2018 at 12:00:34PM +0000, Lorenzo Pieralisi wrote: > The current ARM DT topology description provides the operating system > with a topological view of the system that is based on leaf nodes > representing either cores or threads (in an SMT system) and a > hierarchical set of cluster nodes that creates a hierarchical topology > view of how those cores and threads are grouped. > > As opposed to the ACPI topology description ([1], PPTT table), this > hierarchical representation of clusters does not allow to describe what > topology level actually represents the physical package boundary, which > is a key piece of information to be used by an operating system to > optimize resource allocation and scheduling. Don't the NUMA related bindings already provide this? The only thing I could see this being needed for is servicing (e.g. to replace a bad socket). > > Define an optional, backward compatible boolean property for cluster > nodes that, by reusing the ACPI nomenclature, add to the ARM DT > topological description a binding to define what cluster level > represents a physical package boundary. > > [1] http://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > Cc: Sudeep Holla <sudeep.holla@xxxxxxx> > Cc: Jeremy Linton <jeremy.linton@xxxxxxx> > Cc: Morten Rasmussen <morten.rasmussen@xxxxxxx> > Cc: Frank Rowand <frowand.list@xxxxxxxxx> > Cc: Mark Rutland <mark.rutland@xxxxxxx> > --- > v1->v2: > > - Added dual-package example > - Improved physical-package property description according to review > - Dropped RFC tag > > v1: https://marc.info/?l=linux-arm-kernel&m=151664137216555&w=2 > > Documentation/devicetree/bindings/arm/topology.txt | 432 +++++++++++++++++++++ > 1 file changed, 432 insertions(+) > > diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/arm/topology.txt > index de9eb0486630..09b3b22e57c1 100644 > --- a/Documentation/devicetree/bindings/arm/topology.txt > +++ b/Documentation/devicetree/bindings/arm/topology.txt > @@ -109,6 +109,21 @@ Bindings for cluster/cpu/thread nodes are defined as follows: > The cluster node name must be "clusterN" as described in 2.1 above. > A cluster node can not be a leaf node. > > + Properties for cluster nodes: > + > + - physical-package > + Usage: optional > + Value type: <empty> > + Definition: if present the cluster node represents the > + boundary of a physical package, whether socketed > + or surface mounted. > + The cluster node itself and all its children nodes > + represent a single distinct physical-package unit. > + The cluster node parent and sibling cluster nodes > + (if any) must therefore be considered part of > + separate physical package units in multi > + physical-package systems. > + > A cluster node's child nodes must be: > > - one or more cluster nodes; or > @@ -470,6 +485,423 @@ cpus { > }; > }; > > +Example 3 (ARM 64-bit, 32-cpu system, 2 packages): Can't you expand an existing example. If you have the complex cases, you can derive simple ones. > + > +cpus { > + #size-cells = <0>; > + #address-cells = <2>; > + > + cpu-map { > + cluster0 { > + physical-package; Why not just make this part of the node name? .../cluster0/cluster0/... isn't really the best naming IMO. > + > + cluster0 { > + core0 { > + cpu = <&CPU0>; > + }; -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
