arch/x86/topology.rst

1 .. SPDX-License-Identifier: GPL-2.0
11 The architecture-agnostic topology definitions are in
12 Documentation/admin-guide/cputopology.rst. This file holds x86-specific
17 Needless to say, code should use the generic functions - this file is *only*
28 the past a socket always contained a single package (see below), but with the
35     - packages
36     - cores
37     - threads
48 Package-related topology information in the kernel:
50   - topology_num_threads_per_package()
54   - topology_num_cores_per_package()
58   - topology_max_dies_per_package()
62   - cpuinfo_x86.topo.die_id:
66   - cpuinfo_x86.topo.pkg_id:
74   - cpuinfo_x86.topo.logical_pkg_id:
81   - topology_max_packages():
86   - cpuinfo_x86.topo.llc_id:
88       - On Intel, the first APIC ID of the list of CPUs sharing the Last Level
91       - On AMD, the Node ID or Core Complex ID containing the Last Level
97 A core consists of 1 or more threads. It does not matter whether the threads
98 are SMT- or CMT-type threads.
100 AMDs nomenclature for a CMT core is "Compute Unit". The kernel always uses
101 "core".
105 A thread is a single scheduling unit. It's the equivalent to a logical Linux
108 AMDs nomenclature for CMT threads is "Compute Unit Core". The kernel always
111 Thread-related topology information in the kernel:
113   - topology_core_cpumask():
120   - topology_sibling_cpumask():
122     The cpumask contains all online threads in the core to which a thread
125   - topology_logical_package_id():
129   - topology_physical_package_id():
133   - topology_core_id();
135     The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
150 1) Single Package, Single Core::
152    [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
154 2) Single Package, Dual Core
156    a) One thread per core::
158 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
159 		    -> [core 1] -> [thread 0] -> Linux CPU 1
161    b) Two threads per core::
163 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
164 				-> [thread 1] -> Linux CPU 1
165 		    -> [core 1] -> [thread 0] -> Linux CPU 2
166 				-> [thread 1] -> Linux CPU 3
170 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
171 				-> [thread 1] -> Linux CPU 2
172 		    -> [core 1] -> [thread 0] -> Linux CPU 1
173 				-> [thread 1] -> Linux CPU 3
177 	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
178 				     -> [Compute Unit Core 1] -> Linux CPU 1
179 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
180 				     -> [Compute Unit Core 1] -> Linux CPU 3
182 4) Dual Package, Dual Core
184    a) One thread per core::
186 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
187 		    -> [core 1] -> [thread 0] -> Linux CPU 1
189 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
190 		    -> [core 1] -> [thread 0] -> Linux CPU 3
192    b) Two threads per core::
194 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
195 				-> [thread 1] -> Linux CPU 1
196 		    -> [core 1] -> [thread 0] -> Linux CPU 2
197 				-> [thread 1] -> Linux CPU 3
199 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 4
200 				-> [thread 1] -> Linux CPU 5
201 		    -> [core 1] -> [thread 0] -> Linux CPU 6
202 				-> [thread 1] -> Linux CPU 7
206 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
207 				-> [thread 1] -> Linux CPU 4
208 		    -> [core 1] -> [thread 0] -> Linux CPU 1
209 				-> [thread 1] -> Linux CPU 5
211 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
212 				-> [thread 1] -> Linux CPU 6
213 		    -> [core 1] -> [thread 0] -> Linux CPU 3
214 				-> [thread 1] -> Linux CPU 7
218 	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
219 				     -> [Compute Unit Core 1] -> Linux CPU 1
220 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
221 				     -> [Compute Unit Core 1] -> Linux CPU 3
223 	[node 1] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 4
224 				     -> [Compute Unit Core 1] -> Linux CPU 5
225 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 6
226 				     -> [Compute Unit Core 1] -> Linux CPU 7