xref: /linux/Documentation/devicetree/bindings/numa.txt (revision be092017b6ffbd013f481f915632db6aa9fc3ca3) 
1==============================================================================
2NUMA binding description.
3==============================================================================
4
5==============================================================================
61 - Introduction
7==============================================================================
8
9Systems employing a Non Uniform Memory Access (NUMA) architecture contain
10collections of hardware resources including processors, memory, and I/O buses,
11that comprise what is commonly known as a NUMA node.
12Processor accesses to memory within the local NUMA node is generally faster
13than processor accesses to memory outside of the local NUMA node.
14DT defines interfaces that allow the platform to convey NUMA node
15topology information to OS.
16
17==============================================================================
182 - numa-node-id
19==============================================================================
20
21For the purpose of identification, each NUMA node is associated with a unique
22token known as a node id. For the purpose of this binding
23a node id is a 32-bit integer.
24
25A device node is associated with a NUMA node by the presence of a
26numa-node-id property which contains the node id of the device.
27
28Example:
29	/* numa node 0 */
30	numa-node-id = <0>;
31
32	/* numa node 1 */
33	numa-node-id = <1>;
34
35==============================================================================
363 - distance-map
37==============================================================================
38
39The optional device tree node distance-map describes the relative
40distance (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
62Example:
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==============================================================================
1064 - Example dts
107==============================================================================
108
109Dual socket system consists of 2 boards connected through ccn bus and
110each 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	};
276