0001 ==============================================================================
0002 NUMA binding description.
0003 ==============================================================================
0004
0005 ==============================================================================
0006 1 - Introduction
0007 ==============================================================================
0008
0009 Systems employing a Non Uniform Memory Access (NUMA) architecture contain
0010 collections of hardware resources including processors, memory, and I/O buses,
0011 that comprise what is commonly known as a NUMA node.
0012 Processor accesses to memory within the local NUMA node is generally faster
0013 than processor accesses to memory outside of the local NUMA node.
0014 DT defines interfaces that allow the platform to convey NUMA node
0015 topology information to OS.
0016
0017 ==============================================================================
0018 2 - numa-node-id
0019 ==============================================================================
0020
0021 For the purpose of identification, each NUMA node is associated with a unique
0022 token known as a node id. For the purpose of this binding
0023 a node id is a 32-bit integer.
0024
0025 A device node is associated with a NUMA node by the presence of a
0026 numa-node-id property which contains the node id of the device.
0027
0028 Example:
0029 /* numa node 0 */
0030 numa-node-id = <0>;
0031
0032 /* numa node 1 */
0033 numa-node-id = <1>;
0034
0035 ==============================================================================
0036 3 - distance-map
0037 ==============================================================================
0038
0039 The optional device tree node distance-map describes the relative
0040 distance (memory latency) between all numa nodes.
0041
0042 - compatible : Should at least contain "numa-distance-map-v1".
0043
0044 - distance-matrix
0045 This property defines a matrix to describe the relative distances
0046 between all numa nodes.
0047 It is represented as a list of node pairs and their relative distance.
0048
0049 Note:
0050 1. Each entry represents distance from first node to second node.
0051 The distances are equal in either direction.
0052 2. The distance from a node to self (local distance) is represented
0053 with value 10 and all internode distance should be represented with
0054 a value greater than 10.
0055 3. distance-matrix should have entries in lexicographical ascending
0056 order of nodes.
0057 4. There must be only one device node distance-map which must
0058 reside in the root node.
0059 5. If the distance-map node is not present, a default
0060 distance-matrix is used.
0061
0062 Example:
0063 4 nodes connected in mesh/ring topology as below,
0064
0065 0_______20______1
0066 | |
0067 | |
0068 20 20
0069 | |
0070 | |
0071 |_______________|
0072 3 20 2
0073
0074 if relative distance for each hop is 20,
0075 then internode distance would be,
0076 0 -> 1 = 20
0077 1 -> 2 = 20
0078 2 -> 3 = 20
0079 3 -> 0 = 20
0080 0 -> 2 = 40
0081 1 -> 3 = 40
0082
0083 and dt presentation for this distance matrix is,
0084
0085 distance-map {
0086 compatible = "numa-distance-map-v1";
0087 distance-matrix = <0 0 10>,
0088 <0 1 20>,
0089 <0 2 40>,
0090 <0 3 20>,
0091 <1 0 20>,
0092 <1 1 10>,
0093 <1 2 20>,
0094 <1 3 40>,
0095 <2 0 40>,
0096 <2 1 20>,
0097 <2 2 10>,
0098 <2 3 20>,
0099 <3 0 20>,
0100 <3 1 40>,
0101 <3 2 20>,
0102 <3 3 10>;
0103 };
0104
0105 ==============================================================================
0106 4 - Empty memory nodes
0107 ==============================================================================
0108
0109 Empty memory nodes, which no memory resides in, are allowed. There are no
0110 device nodes for these empty memory nodes. However, the NUMA node IDs and
0111 distance maps are still valid and memory may be added into them through
0112 hotplug afterwards.
0113
0114 Example:
0115
0116 memory@0 {
0117 device_type = "memory";
0118 reg = <0x0 0x0 0x0 0x80000000>;
0119 numa-node-id = <0>;
0120 };
0121
0122 memory@80000000 {
0123 device_type = "memory";
0124 reg = <0x0 0x80000000 0x0 0x80000000>;
0125 numa-node-id = <1>;
0126 };
0127
0128 /* Empty memory node 2 and 3 */
0129 distance-map {
0130 compatible = "numa-distance-map-v1";
0131 distance-matrix = <0 0 10>,
0132 <0 1 20>,
0133 <0 2 40>,
0134 <0 3 20>,
0135 <1 0 20>,
0136 <1 1 10>,
0137 <1 2 20>,
0138 <1 3 40>,
0139 <2 0 40>,
0140 <2 1 20>,
0141 <2 2 10>,
0142 <2 3 20>,
0143 <3 0 20>,
0144 <3 1 40>,
0145 <3 2 20>,
0146 <3 3 10>;
0147 };
0148
0149 ==============================================================================
0150 5 - Example dts
0151 ==============================================================================
0152
0153 Dual socket system consists of 2 boards connected through ccn bus and
0154 each board having one socket/soc of 8 cpus, memory and pci bus.
0155
0156 memory@c00000 {
0157 device_type = "memory";
0158 reg = <0x0 0xc00000 0x0 0x80000000>;
0159 /* node 0 */
0160 numa-node-id = <0>;
0161 };
0162
0163 memory@10000000000 {
0164 device_type = "memory";
0165 reg = <0x100 0x0 0x0 0x80000000>;
0166 /* node 1 */
0167 numa-node-id = <1>;
0168 };
0169
0170 cpus {
0171 #address-cells = <2>;
0172 #size-cells = <0>;
0173
0174 cpu@0 {
0175 device_type = "cpu";
0176 compatible = "arm,armv8";
0177 reg = <0x0 0x0>;
0178 enable-method = "psci";
0179 /* node 0 */
0180 numa-node-id = <0>;
0181 };
0182 cpu@1 {
0183 device_type = "cpu";
0184 compatible = "arm,armv8";
0185 reg = <0x0 0x1>;
0186 enable-method = "psci";
0187 numa-node-id = <0>;
0188 };
0189 cpu@2 {
0190 device_type = "cpu";
0191 compatible = "arm,armv8";
0192 reg = <0x0 0x2>;
0193 enable-method = "psci";
0194 numa-node-id = <0>;
0195 };
0196 cpu@3 {
0197 device_type = "cpu";
0198 compatible = "arm,armv8";
0199 reg = <0x0 0x3>;
0200 enable-method = "psci";
0201 numa-node-id = <0>;
0202 };
0203 cpu@4 {
0204 device_type = "cpu";
0205 compatible = "arm,armv8";
0206 reg = <0x0 0x4>;
0207 enable-method = "psci";
0208 numa-node-id = <0>;
0209 };
0210 cpu@5 {
0211 device_type = "cpu";
0212 compatible = "arm,armv8";
0213 reg = <0x0 0x5>;
0214 enable-method = "psci";
0215 numa-node-id = <0>;
0216 };
0217 cpu@6 {
0218 device_type = "cpu";
0219 compatible = "arm,armv8";
0220 reg = <0x0 0x6>;
0221 enable-method = "psci";
0222 numa-node-id = <0>;
0223 };
0224 cpu@7 {
0225 device_type = "cpu";
0226 compatible = "arm,armv8";
0227 reg = <0x0 0x7>;
0228 enable-method = "psci";
0229 numa-node-id = <0>;
0230 };
0231 cpu@8 {
0232 device_type = "cpu";
0233 compatible = "arm,armv8";
0234 reg = <0x0 0x8>;
0235 enable-method = "psci";
0236 /* node 1 */
0237 numa-node-id = <1>;
0238 };
0239 cpu@9 {
0240 device_type = "cpu";
0241 compatible = "arm,armv8";
0242 reg = <0x0 0x9>;
0243 enable-method = "psci";
0244 numa-node-id = <1>;
0245 };
0246 cpu@a {
0247 device_type = "cpu";
0248 compatible = "arm,armv8";
0249 reg = <0x0 0xa>;
0250 enable-method = "psci";
0251 numa-node-id = <1>;
0252 };
0253 cpu@b {
0254 device_type = "cpu";
0255 compatible = "arm,armv8";
0256 reg = <0x0 0xb>;
0257 enable-method = "psci";
0258 numa-node-id = <1>;
0259 };
0260 cpu@c {
0261 device_type = "cpu";
0262 compatible = "arm,armv8";
0263 reg = <0x0 0xc>;
0264 enable-method = "psci";
0265 numa-node-id = <1>;
0266 };
0267 cpu@d {
0268 device_type = "cpu";
0269 compatible = "arm,armv8";
0270 reg = <0x0 0xd>;
0271 enable-method = "psci";
0272 numa-node-id = <1>;
0273 };
0274 cpu@e {
0275 device_type = "cpu";
0276 compatible = "arm,armv8";
0277 reg = <0x0 0xe>;
0278 enable-method = "psci";
0279 numa-node-id = <1>;
0280 };
0281 cpu@f {
0282 device_type = "cpu";
0283 compatible = "arm,armv8";
0284 reg = <0x0 0xf>;
0285 enable-method = "psci";
0286 numa-node-id = <1>;
0287 };
0288 };
0289
0290 pcie0: pcie0@848000000000 {
0291 compatible = "arm,armv8";
0292 device_type = "pci";
0293 bus-range = <0 255>;
0294 #size-cells = <2>;
0295 #address-cells = <3>;
0296 reg = <0x8480 0x00000000 0 0x10000000>; /* Configuration space */
0297 ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>;
0298 /* node 0 */
0299 numa-node-id = <0>;
0300 };
0301
0302 pcie1: pcie1@948000000000 {
0303 compatible = "arm,armv8";
0304 device_type = "pci";
0305 bus-range = <0 255>;
0306 #size-cells = <2>;
0307 #address-cells = <3>;
0308 reg = <0x9480 0x00000000 0 0x10000000>; /* Configuration space */
0309 ranges = <0x03000000 0x9010 0x00000000 0x9010 0x00000000 0x70 0x00000000>;
0310 /* node 1 */
0311 numa-node-id = <1>;
0312 };
0313
0314 distance-map {
0315 compatible = "numa-distance-map-v1";
0316 distance-matrix = <0 0 10>,
0317 <0 1 20>,
0318 <1 1 10>;
0319 };
