Commit 848942cb authored by Changbin Du's avatar Changbin Du Committed by Jonathan Corbet
Browse files

Documentation: x86: convert topology.txt to reST 



This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.

Signed-off-by: default avatarChangbin Du <changbin.du@gmail.com>
Reviewed-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent f1f238a9

Documentation/x86/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -9,3 +9,4 @@ x86-specific Documentation 
   :numbered:



   boot

   topology

Documentation/x86/topology.txt→Documentation/x86/topology.rst

+48 −44
Original line number Diff line number Diff line 
.. SPDX-License-Identifier: GPL-2.0



============

x86 Topology

============
@@ -33,8 +36,8 @@ The topology of a system is described in the units of: 
    - cores

    - threads



* Package:



Package

=======

Packages contain a number of cores plus shared resources, e.g. DRAM

controller, shared caches etc.
@@ -66,6 +69,7 @@ The topology of a system is described in the units of: 
  - cpu_llc_id:



    A per-CPU variable containing:



      - On Intel, the first APIC ID of the list of CPUs sharing the Last Level

        Cache
@@ -73,8 +77,8 @@ The topology of a system is described in the units of: 
        Cache. In general, it is a number identifying an LLC uniquely on the

        system.



* Cores:



Cores

=====

A core consists of 1 or more threads. It does not matter whether the threads

are SMT- or CMT-type threads.
@@ -86,13 +90,13 @@ The topology of a system is described in the units of: 
  - smp_num_siblings:



    The number of threads in a core. The number of threads in a package can be

    calculated by:

    calculated by::



	threads_per_package = cpuinfo_x86.x86_max_cores * smp_num_siblings





* Threads:



Threads

=======

A thread is a single scheduling unit. It's the equivalent to a logical Linux

CPU.
@@ -129,41 +133,41 @@ The topology of a system is described in the units of: 




System topology examples

========================



Note:



.. note::

  The alternative Linux CPU enumeration depends on how the BIOS enumerates the

  threads. Many BIOSes enumerate all threads 0 first and then all threads 1.

  That has the "advantage" that the logical Linux CPU numbers of threads 0 stay

  the same whether threads are enabled or not. That's merely an implementation

  detail and has no practical impact.



1) Single Package, Single Core

1) Single Package, Single Core::



   [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0



2) Single Package, Dual Core



   a) One thread per core

   a) One thread per core::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

		    -> [core 1] -> [thread 0] -> Linux CPU 1



   b) Two threads per core

   b) Two threads per core::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

				-> [thread 1] -> Linux CPU 1

		    -> [core 1] -> [thread 0] -> Linux CPU 2

				-> [thread 1] -> Linux CPU 3



      Alternative enumeration:

      Alternative enumeration::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

				-> [thread 1] -> Linux CPU 2

		    -> [core 1] -> [thread 0] -> Linux CPU 1

				-> [thread 1] -> Linux CPU 3



      AMD nomenclature for CMT systems:

      AMD nomenclature for CMT systems::



	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0

				     -> [Compute Unit Core 1] -> Linux CPU 1
@@ -172,7 +176,7 @@ detail and has no practical impact. 


4) Dual Package, Dual Core



   a) One thread per core

   a) One thread per core::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

		    -> [core 1] -> [thread 0] -> Linux CPU 1
@@ -180,7 +184,7 @@ detail and has no practical impact. 
	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2

		    -> [core 1] -> [thread 0] -> Linux CPU 3



   b) Two threads per core

   b) Two threads per core::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

				-> [thread 1] -> Linux CPU 1
@@ -192,7 +196,7 @@ detail and has no practical impact. 
		    -> [core 1] -> [thread 0] -> Linux CPU 6

				-> [thread 1] -> Linux CPU 7



      Alternative enumeration:

      Alternative enumeration::



	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0

				-> [thread 1] -> Linux CPU 4
@@ -204,7 +208,7 @@ detail and has no practical impact. 
		    -> [core 1] -> [thread 0] -> Linux CPU 3

				-> [thread 1] -> Linux CPU 7



      AMD nomenclature for CMT systems:

      AMD nomenclature for CMT systems::



	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0

				     -> [Compute Unit Core 1] -> Linux CPU 1

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