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 - Empty memory nodes
107 ==============================================================================
108
109 Empty memory nodes, which no memory resides in, are allowed. There are no
110 device nodes for these empty memory nodes. However, the NUMA node IDs and
111 distance maps are still valid and memory may be added into them through
112 hotplug afterwards.
113
114 Example:
115
116 memory@0 {
117 device_type = "memory";
118 reg = <0x0 0x0 0x0 0x80000000>;
119 numa-node-id = <0>;
120 };
121
122 memory@80000000 {
123 device_type = "memory";
124 reg = <0x0 0x80000000 0x0 0x80000000>;
125 numa-node-id = <1>;
126 };
127
128 /* Empty memory node 2 and 3 */
129 distance-map {
130 compatible = "numa-distance-map-v1";
131 distance-matrix = <0 0 10>,
132 <0 1 20>,
133 <0 2 40>,
134 <0 3 20>,
135 <1 0 20>,
136 <1 1 10>,
137 <1 2 20>,
138 <1 3 40>,
139 <2 0 40>,
140 <2 1 20>,
141 <2 2 10>,
142 <2 3 20>,
143 <3 0 20>,
144 <3 1 40>,
145 <3 2 20>,
146 <3 3 10>;
147 };
148
149 ==============================================================================
150 5 - Example dts
151 ==============================================================================
152
153 Dual socket system consists of 2 boards connected through ccn bus and
154 each board having one socket/soc of 8 cpus, memory and pci bus.
155
156 memory@c00000 {
157 device_type = "memory";
158 reg = <0x0 0xc00000 0x0 0x80000000>;
159 /* node 0 */
160 numa-node-id = <0>;
161 };
162
163 memory@10000000000 {
164 device_type = "memory";
165 reg = <0x100 0x0 0x0 0x80000000>;
166 /* node 1 */
167 numa-node-id = <1>;
168 };
169
170 cpus {
171 #address-cells = <2>;
172 #size-cells = <0>;
173
174 cpu@0 {
175 device_type = "cpu";
176 compatible = "arm,armv8";
177 reg = <0x0 0x0>;
178 enable-method = "psci";
179 /* node 0 */
180 numa-node-id = <0>;
181 };
182 cpu@1 {
183 device_type = "cpu";
184 compatible = "arm,armv8";
185 reg = <0x0 0x1>;
186 enable-method = "psci";
187 numa-node-id = <0>;
188 };
189 cpu@2 {
190 device_type = "cpu";
191 compatible = "arm,armv8";
192 reg = <0x0 0x2>;
193 enable-method = "psci";
194 numa-node-id = <0>;
195 };
196 cpu@3 {
197 device_type = "cpu";
198 compatible = "arm,armv8";
199 reg = <0x0 0x3>;
200 enable-method = "psci";
201 numa-node-id = <0>;
202 };
203 cpu@4 {
204 device_type = "cpu";
205 compatible = "arm,armv8";
206 reg = <0x0 0x4>;
207 enable-method = "psci";
208 numa-node-id = <0>;
209 };
210 cpu@5 {
211 device_type = "cpu";
212 compatible = "arm,armv8";
213 reg = <0x0 0x5>;
214 enable-method = "psci";
215 numa-node-id = <0>;
216 };
217 cpu@6 {
218 device_type = "cpu";
219 compatible = "arm,armv8";
220 reg = <0x0 0x6>;
221 enable-method = "psci";
222 numa-node-id = <0>;
223 };
224 cpu@7 {
225 device_type = "cpu";
226 compatible = "arm,armv8";
227 reg = <0x0 0x7>;
228 enable-method = "psci";
229 numa-node-id = <0>;
230 };
231 cpu@8 {
232 device_type = "cpu";
233 compatible = "arm,armv8";
234 reg = <0x0 0x8>;
235 enable-method = "psci";
236 /* node 1 */
237 numa-node-id = <1>;
238 };
239 cpu@9 {
240 device_type = "cpu";
241 compatible = "arm,armv8";
242 reg = <0x0 0x9>;
243 enable-method = "psci";
244 numa-node-id = <1>;
245 };
246 cpu@a {
247 device_type = "cpu";
248 compatible = "arm,armv8";
249 reg = <0x0 0xa>;
250 enable-method = "psci";
251 numa-node-id = <1>;
252 };
253 cpu@b {
254 device_type = "cpu";
255 compatible = "arm,armv8";
256 reg = <0x0 0xb>;
257 enable-method = "psci";
258 numa-node-id = <1>;
259 };
260 cpu@c {
261 device_type = "cpu";
262 compatible = "arm,armv8";
263 reg = <0x0 0xc>;
264 enable-method = "psci";
265 numa-node-id = <1>;
266 };
267 cpu@d {
268 device_type = "cpu";
269 compatible = "arm,armv8";
270 reg = <0x0 0xd>;
271 enable-method = "psci";
272 numa-node-id = <1>;
273 };
274 cpu@e {
275 device_type = "cpu";
276 compatible = "arm,armv8";
277 reg = <0x0 0xe>;
278 enable-method = "psci";
279 numa-node-id = <1>;
280 };
281 cpu@f {
282 device_type = "cpu";
283 compatible = "arm,armv8";
284 reg = <0x0 0xf>;
285 enable-method = "psci";
286 numa-node-id = <1>;
287 };
288 };
289
290 pcie0: pcie0@848000000000 {
291 compatible = "arm,armv8";
292 device_type = "pci";
293 bus-range = <0 255>;
294 #size-cells = <2>;
295 #address-cells = <3>;
296 reg = <0x8480 0x00000000 0 0x10000000>; /* Configuration space */
297 ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>;
298 /* node 0 */
299 numa-node-id = <0>;
300 };
301
302 pcie1: pcie1@948000000000 {
303 compatible = "arm,armv8";
304 device_type = "pci";
305 bus-range = <0 255>;
306 #size-cells = <2>;
307 #address-cells = <3>;
308 reg = <0x9480 0x00000000 0 0x10000000>; /* Configuration space */
309 ranges = <0x03000000 0x9010 0x00000000 0x9010 0x00000000 0x70 0x00000000>;
310 /* node 1 */
311 numa-node-id = <1>;
312 };
313
314 distance-map {
315 compatible = "numa-distance-map-v1";
316 distance-matrix = <0 0 10>,
317 <0 1 20>,
318 <1 1 10>;
319 };
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