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*
35     - packages
36     - cores
37     - threads
48 Package-related topology information in the kernel:
50   - cpuinfo_x86.x86_max_cores:
54   - cpuinfo_x86.x86_max_dies:
58   - cpuinfo_x86.topo.die_id:
62   - cpuinfo_x86.topo.pkg_id:
70   - cpuinfo_x86.topo.logical_pkg_id:
77   - topology_max_packages():
82   - cpuinfo_x86.topo.llc_id:
84       - On Intel, the first APIC ID of the list of CPUs sharing the Last Level
87       - On AMD, the Node ID or Core Complex ID containing the Last Level
93 A core consists of 1 or more threads. It does not matter whether the threads
94 are SMT- or CMT-type threads.
96 AMDs nomenclature for a CMT core is "Compute Unit". The kernel always uses
97 "core".
99 Core-related topology information in the kernel:
101   - smp_num_siblings:
103     The number of threads in a core. The number of threads in a package can be
112 CPU.
114 AMDs nomenclature for CMT threads is "Compute Unit Core". The kernel always
117 Thread-related topology information in the kernel:
119   - topology_core_cpumask():
126   - topology_sibling_cpumask():
128     The cpumask contains all online threads in the core to which a thread
131   - topology_logical_package_id():
135   - topology_physical_package_id():
139   - topology_core_id();
141     The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
150   The alternative Linux CPU enumeration depends on how the BIOS enumerates the
152   That has the "advantage" that the logical Linux CPU numbers of threads 0 stay
156 1) Single Package, Single Core::
158    [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
160 2) Single Package, Dual Core
162    a) One thread per core::
164 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
165 		    -> [core 1] -> [thread 0] -> Linux CPU 1
167    b) Two threads per core::
169 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
170 				-> [thread 1] -> Linux CPU 1
171 		    -> [core 1] -> [thread 0] -> Linux CPU 2
172 				-> [thread 1] -> Linux CPU 3
176 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
177 				-> [thread 1] -> Linux CPU 2
178 		    -> [core 1] -> [thread 0] -> Linux CPU 1
179 				-> [thread 1] -> Linux CPU 3
183 	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
184 				     -> [Compute Unit Core 1] -> Linux CPU 1
185 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
186 				     -> [Compute Unit Core 1] -> Linux CPU 3
188 4) Dual Package, Dual Core
190    a) One thread per core::
192 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
193 		    -> [core 1] -> [thread 0] -> Linux CPU 1
195 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
196 		    -> [core 1] -> [thread 0] -> Linux CPU 3
198    b) Two threads per core::
200 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
201 				-> [thread 1] -> Linux CPU 1
202 		    -> [core 1] -> [thread 0] -> Linux CPU 2
203 				-> [thread 1] -> Linux CPU 3
205 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 4
206 				-> [thread 1] -> Linux CPU 5
207 		    -> [core 1] -> [thread 0] -> Linux CPU 6
208 				-> [thread 1] -> Linux CPU 7
212 	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
213 				-> [thread 1] -> Linux CPU 4
214 		    -> [core 1] -> [thread 0] -> Linux CPU 1
215 				-> [thread 1] -> Linux CPU 5
217 	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
218 				-> [thread 1] -> Linux CPU 6
219 		    -> [core 1] -> [thread 0] -> Linux CPU 3
220 				-> [thread 1] -> Linux CPU 7
224 	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
225 				     -> [Compute Unit Core 1] -> Linux CPU 1
226 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
227 				     -> [Compute Unit Core 1] -> Linux CPU 3
229 	[node 1] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 4
230 				     -> [Compute Unit Core 1] -> Linux CPU 5
231 		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 6
232 				     -> [Compute Unit Core 1] -> Linux CPU 7