Documentation/devicetree/bindings/numa.txt

   1 ==============================================================================
   2 NUMA binding description.
   3 ==============================================================================
   4
   5 ==============================================================================
   6 1 - Introduction
   7 ==============================================================================
   8
   9 Systems employing a Non Uniform Memory Access (NUMA) architecture contain
  10 collections of hardware resources including processors, memory, and I/O buses,
  11 that comprise what is commonly known as a NUMA node.
  12 Processor accesses to memory within the local NUMA node is generally faster
  13 than processor accesses to memory outside of the local NUMA node.
  14 DT defines interfaces that allow the platform to convey NUMA node
  15 topology information to OS.
  16
  17 ==============================================================================
  18 2 - numa-node-id
  19 ==============================================================================
  20
  21 For the purpose of identification, each NUMA node is associated with a unique
  22 token known as a node id. For the purpose of this binding
  23 a node id is a 32-bit integer.
  24
  25 A device node is associated with a NUMA node by the presence of a
  26 numa-node-id property which contains the node id of the device.
  27
  28 Example:
  29         /* numa node 0 */
  30         numa-node-id = <0>;
  31
  32         /* numa node 1 */
  33         numa-node-id = <1>;
  34
  35 ==============================================================================
  36 3 - distance-map
  37 ==============================================================================
  38
  39 The optional device tree node distance-map describes the relative
  40 distance (memory latency) between all numa nodes.
  41
  42 - compatible : Should at least contain "numa-distance-map-v1".
  43
  44 - distance-matrix
  45   This property defines a matrix to describe the relative distances
  46   between all numa nodes.
  47   It is represented as a list of node pairs and their relative distance.
  48
  49   Note:
  50         1. Each entry represents distance from first node to second node.
  51         The distances are equal in either direction.
  52         2. The distance from a node to self (local distance) is represented
  53         with value 10 and all internode distance should be represented with
  54         a value greater than 10.
  55         3. distance-matrix should have entries in lexicographical ascending
  56         order of nodes.
  57         4. There must be only one device node distance-map which must
  58         reside in the root node.
  59         5. If the distance-map node is not present, a default
  60         distance-matrix is used.
  61
  62 Example:
  63         4 nodes connected in mesh/ring topology as below,
  64
  65                 0_______20______1
  66                 |               |
  67                 |               |
  68                 20             20
  69                 |               |
  70                 |               |
  71                 |_______________|
  72                 3       20      2
  73
  74         if relative distance for each hop is 20,
  75         then internode distance would be,
  76               0 -> 1 = 20
  77               1 -> 2 = 20
  78               2 -> 3 = 20
  79               3 -> 0 = 20
  80               0 -> 2 = 40
  81               1 -> 3 = 40
  82
  83      and dt presentation for this distance matrix is,
  84
  85                 distance-map {
  86                          compatible = "numa-distance-map-v1";
  87                          distance-matrix = <0 0  10>,
  88                                            <0 1  20>,
  89                                            <0 2  40>,
  90                                            <0 3  20>,
  91                                            <1 0  20>,
  92                                            <1 1  10>,
  93                                            <1 2  20>,
  94                                            <1 3  40>,
  95                                            <2 0  40>,
  96                                            <2 1  20>,
  97                                            <2 2  10>,
  98                                            <2 3  20>,
  99                                            <3 0  20>,
 100                                            <3 1  40>,
 101                                            <3 2  20>,
 102                                            <3 3  10>;
 103                 };
 104
 105 ==============================================================================
 106 4 - Example dts
 107 ==============================================================================
 108
 109 Dual socket system consists of 2 boards connected through ccn bus and
 110 each board having one socket/soc of 8 cpus, memory and pci bus.
 111
 112         memory@c00000 {
 113                 device_type = "memory";
 114                 reg = <0x0 0xc00000 0x0 0x80000000>;
 115                 /* node 0 */
 116                 numa-node-id = <0>;
 117         };
 118
 119         memory@10000000000 {
 120                 device_type = "memory";
 121                 reg = <0x100 0x0 0x0 0x80000000>;
 122                 /* node 1 */
 123                 numa-node-id = <1>;
 124         };
 125
 126         cpus {
 127                 #address-cells = <2>;
 128                 #size-cells = <0>;
 129
 130                 cpu@0 {
 131                         device_type = "cpu";
 132                         compatible =  "arm,armv8";
 133                         reg = <0x0 0x0>;
 134                         enable-method = "psci";
 135                         /* node 0 */
 136                         numa-node-id = <0>;
 137                 };
 138                 cpu@1 {
 139                         device_type = "cpu";
 140                         compatible =  "arm,armv8";
 141                         reg = <0x0 0x1>;
 142                         enable-method = "psci";
 143                         numa-node-id = <0>;
 144                 };
 145                 cpu@2 {
 146                         device_type = "cpu";
 147                         compatible =  "arm,armv8";
 148                         reg = <0x0 0x2>;
 149                         enable-method = "psci";
 150                         numa-node-id = <0>;
 151                 };
 152                 cpu@3 {
 153                         device_type = "cpu";
 154                         compatible =  "arm,armv8";
 155                         reg = <0x0 0x3>;
 156                         enable-method = "psci";
 157                         numa-node-id = <0>;
 158                 };
 159                 cpu@4 {
 160                         device_type = "cpu";
 161                         compatible =  "arm,armv8";
 162                         reg = <0x0 0x4>;
 163                         enable-method = "psci";
 164                         numa-node-id = <0>;
 165                 };
 166                 cpu@5 {
 167                         device_type = "cpu";
 168                         compatible =  "arm,armv8";
 169                         reg = <0x0 0x5>;
 170                         enable-method = "psci";
 171                         numa-node-id = <0>;
 172                 };
 173                 cpu@6 {
 174                         device_type = "cpu";
 175                         compatible =  "arm,armv8";
 176                         reg = <0x0 0x6>;
 177                         enable-method = "psci";
 178                         numa-node-id = <0>;
 179                 };
 180                 cpu@7 {
 181                         device_type = "cpu";
 182                         compatible =  "arm,armv8";
 183                         reg = <0x0 0x7>;
 184                         enable-method = "psci";
 185                         numa-node-id = <0>;
 186                 };
 187                 cpu@8 {
 188                         device_type = "cpu";
 189                         compatible =  "arm,armv8";
 190                         reg = <0x0 0x8>;
 191                         enable-method = "psci";
 192                         /* node 1 */
 193                         numa-node-id = <1>;
 194                 };
 195                 cpu@9 {
 196                         device_type = "cpu";
 197                         compatible =  "arm,armv8";
 198                         reg = <0x0 0x9>;
 199                         enable-method = "psci";
 200                         numa-node-id = <1>;
 201                 };
 202                 cpu@a {
 203                         device_type = "cpu";
 204                         compatible =  "arm,armv8";
 205                         reg = <0x0 0xa>;
 206                         enable-method = "psci";
 207                         numa-node-id = <1>;
 208                 };
 209                 cpu@b {
 210                         device_type = "cpu";
 211                         compatible =  "arm,armv8";
 212                         reg = <0x0 0xb>;
 213                         enable-method = "psci";
 214                         numa-node-id = <1>;
 215                 };
 216                 cpu@c {
 217                         device_type = "cpu";
 218                         compatible =  "arm,armv8";
 219                         reg = <0x0 0xc>;
 220                         enable-method = "psci";
 221                         numa-node-id = <1>;
 222                 };
 223                 cpu@d {
 224                         device_type = "cpu";
 225                         compatible =  "arm,armv8";
 226                         reg = <0x0 0xd>;
 227                         enable-method = "psci";
 228                         numa-node-id = <1>;
 229                 };
 230                 cpu@e {
 231                         device_type = "cpu";
 232                         compatible =  "arm,armv8";
 233                         reg = <0x0 0xe>;
 234                         enable-method = "psci";
 235                         numa-node-id = <1>;
 236                 };
 237                 cpu@f {
 238                         device_type = "cpu";
 239                         compatible =  "arm,armv8";
 240                         reg = <0x0 0xf>;
 241                         enable-method = "psci";
 242                         numa-node-id = <1>;
 243                 };
 244         };
 245
 246         pcie0: pcie0@848000000000 {
 247                 compatible = "arm,armv8";
 248                 device_type = "pci";
 249                 bus-range = <0 255>;
 250                 #size-cells = <2>;
 251                 #address-cells = <3>;
 252                 reg = <0x8480 0x00000000 0 0x10000000>;  /* Configuration space */
 253                 ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>;
 254                 /* node 0 */
 255                 numa-node-id = <0>;
 256         };
 257
 258         pcie1: pcie1@948000000000 {
 259                 compatible = "arm,armv8";
 260                 device_type = "pci";
 261                 bus-range = <0 255>;
 262                 #size-cells = <2>;
 263                 #address-cells = <3>;
 264                 reg = <0x9480 0x00000000 0 0x10000000>;  /* Configuration space */
 265                 ranges = <0x03000000 0x9010 0x00000000 0x9010 0x00000000 0x70 0x00000000>;
 266                 /* node 1 */
 267                 numa-node-id = <1>;
 268         };
 269
 270         distance-map {
 271                 compatible = "numa-distance-map-v1";
 272                 distance-matrix = <0 0 10>,
 273                                   <0 1 20>,
 274                                   <1 1 10>;
 275         };