[PATCH v4 39/63] Documentation: x86: convert topology.txt to reST

[Changbin Du]

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

Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
 Documentation/x86/index.rst    |   1 +
 Documentation/x86/topology.rst | 228 +++++++++++++++++++++++++++++++++
 Documentation/x86/topology.txt | 217 -------------------------------
 3 files changed, 229 insertions(+), 217 deletions(-)
 create mode 100644 Documentation/x86/topology.rst
 delete mode 100644 Documentation/x86/topology.txt

diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index 8f08caf4fbbb..2033791e53bc 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -9,3 +9,4 @@ Linux x86 Support
    :numbered:
 
    boot
+   topology
diff --git a/Documentation/x86/topology.rst b/Documentation/x86/topology.rst
new file mode 100644
index 000000000000..1df5f56f4882
--- /dev/null
+++ b/Documentation/x86/topology.rst
@@ -0,0 +1,228 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+x86 Topology
+============
+
+This documents and clarifies the main aspects of x86 topology modelling and
+representation in the kernel. Update/change when doing changes to the
+respective code.
+
+The architecture-agnostic topology definitions are in
+Documentation/cputopology.txt. This file holds x86-specific
+differences/specialities which must not necessarily apply to the generic
+definitions. Thus, the way to read up on Linux topology on x86 is to start
+with the generic one and look at this one in parallel for the x86 specifics.
+
+Needless to say, code should use the generic functions - this file is *only*
+here to *document* the inner workings of x86 topology.
+
+Started by Thomas Gleixner <tglx@xxxxxxxxxxxxx> and Borislav Petkov <bp@xxxxxxxxx>.
+
+The main aim of the topology facilities is to present adequate interfaces to
+code which needs to know/query/use the structure of the running system wrt
+threads, cores, packages, etc.
+
+The kernel does not care about the concept of physical sockets because a
+socket has no relevance to software. It's an electromechanical component. In
+the past a socket always contained a single package (see below), but with the
+advent of Multi Chip Modules (MCM) a socket can hold more than one package. So
+there might be still references to sockets in the code, but they are of
+historical nature and should be cleaned up.
+
+The topology of a system is described in the units of:
+
+    - packages
+    - cores
+    - threads
+
+Package
+=======
+
+Packages contain a number of cores plus shared resources, e.g. DRAM
+controller, shared caches etc.
+
+AMD nomenclature for package is 'Node'.
+
+Package-related topology information in the kernel:
+
+  - cpuinfo_x86.x86_max_cores:
+
+    The number of cores in a package. This information is retrieved via CPUID.
+
+  - cpuinfo_x86.phys_proc_id:
+
+    The physical ID of the package. This information is retrieved via CPUID
+    and deduced from the APIC IDs of the cores in the package.
+
+  - cpuinfo_x86.logical_id:
+
+    The logical ID of the package. As we do not trust BIOSes to enumerate the
+    packages in a consistent way, we introduced the concept of logical package
+    ID so we can sanely calculate the number of maximum possible packages in
+    the system and have the packages enumerated linearly.
+
+  - topology_max_packages():
+
+    The maximum possible number of packages in the system. Helpful for per
+    package facilities to preallocate per package information.
+
+  - cpu_llc_id:
+
+    A per-CPU variable containing:
+
+    - On Intel, the first APIC ID of the list of CPUs sharing the Last Level
+      Cache.
+
+    - On AMD, the Node ID or Core Complex ID containing the Last Level
+      Cache. In general, it is a number identifying an LLC uniquely on the
+      system.
+
+Cores
+=====
+
+A core consists of 1 or more threads. It does not matter whether the threads
+are SMT- or CMT-type threads.
+
+AMDs nomenclature for a CMT core is "Compute Unit". The kernel always uses
+"core".
+
+Core-related topology information in the kernel:
+
+  - smp_num_siblings:
+
+    The number of threads in a core. The number of threads in a package can be
+    calculated by::
+
+      threads_per_package = cpuinfo_x86.x86_max_cores * smp_num_siblings
+
+
+Threads
+=======
+
+A thread is a single scheduling unit. It's the equivalent to a logical Linux
+CPU.
+
+AMDs nomenclature for CMT threads is "Compute Unit Core". The kernel always
+uses "thread".
+
+Thread-related topology information in the kernel:
+
+  - topology_core_cpumask():
+
+    The cpumask contains all online threads in the package to which a thread
+    belongs.
+
+    The number of online threads is also printed in /proc/cpuinfo "siblings."
+
+  - topology_sibling_cpumask():
+
+    The cpumask contains all online threads in the core to which a thread
+    belongs.
+
+  - topology_logical_package_id():
+
+    The logical package ID to which a thread belongs.
+
+  - topology_physical_package_id():
+
+    The physical package ID to which a thread belongs.
+
+  - topology_core_id();
+
+    The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
+    "core_id."
+
+
+
+System topology examples
+========================
+
+.. 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
+::
+
+   [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
+
+2) Single Package, Dual 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
+  ::
+
+    [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::
+
+    [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::
+
+    [node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
+              -> [Compute Unit Core 1] -> Linux CPU 1
+      -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
+              -> [Compute Unit Core 1] -> Linux CPU 3
+
+4) Dual Package, Dual Core
+
+  a) One thread per core
+  ::
+
+    [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
+          -> [core 1] -> [thread 0] -> Linux CPU 1
+
+    [package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
+          -> [core 1] -> [thread 0] -> Linux CPU 3
+
+  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
+
+    [package 1] -> [core 0] -> [thread 0] -> Linux CPU 4
+          -> [thread 1] -> Linux CPU 5
+          -> [core 1] -> [thread 0] -> Linux CPU 6
+          -> [thread 1] -> Linux CPU 7
+
+  Alternative enumeration::
+
+    [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
+          -> [thread 1] -> Linux CPU 4
+          -> [core 1] -> [thread 0] -> Linux CPU 1
+          -> [thread 1] -> Linux CPU 5
+
+    [package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
+          -> [thread 1] -> Linux CPU 6
+          -> [core 1] -> [thread 0] -> Linux CPU 3
+          -> [thread 1] -> Linux CPU 7
+
+  AMD nomenclature for CMT systems::
+
+    [node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
+              -> [Compute Unit Core 1] -> Linux CPU 1
+      -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
+              -> [Compute Unit Core 1] -> Linux CPU 3
+
+    [node 1] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 4
+              -> [Compute Unit Core 1] -> Linux CPU 5
+      -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 6
+              -> [Compute Unit Core 1] -> Linux CPU 7
diff --git a/Documentation/x86/topology.txt b/Documentation/x86/topology.txt
deleted file mode 100644
index 2953e3ec9a02..000000000000
--- a/Documentation/x86/topology.txt
+++ /dev/null
@@ -1,217 +0,0 @@
-x86 Topology
-============
-
-This documents and clarifies the main aspects of x86 topology modelling and
-representation in the kernel. Update/change when doing changes to the
-respective code.
-
-The architecture-agnostic topology definitions are in
-Documentation/cputopology.txt. This file holds x86-specific
-differences/specialities which must not necessarily apply to the generic
-definitions. Thus, the way to read up on Linux topology on x86 is to start
-with the generic one and look at this one in parallel for the x86 specifics.
-
-Needless to say, code should use the generic functions - this file is *only*
-here to *document* the inner workings of x86 topology.
-
-Started by Thomas Gleixner <tglx@xxxxxxxxxxxxx> and Borislav Petkov <bp@xxxxxxxxx>.
-
-The main aim of the topology facilities is to present adequate interfaces to
-code which needs to know/query/use the structure of the running system wrt
-threads, cores, packages, etc.
-
-The kernel does not care about the concept of physical sockets because a
-socket has no relevance to software. It's an electromechanical component. In
-the past a socket always contained a single package (see below), but with the
-advent of Multi Chip Modules (MCM) a socket can hold more than one package. So
-there might be still references to sockets in the code, but they are of
-historical nature and should be cleaned up.
-
-The topology of a system is described in the units of:
-
-    - packages
-    - cores
-    - threads
-
-* Package:
-
-  Packages contain a number of cores plus shared resources, e.g. DRAM
-  controller, shared caches etc.
-
-  AMD nomenclature for package is 'Node'.
-
-  Package-related topology information in the kernel:
-
-  - cpuinfo_x86.x86_max_cores:
-
-    The number of cores in a package. This information is retrieved via CPUID.
-
-  - cpuinfo_x86.phys_proc_id:
-
-    The physical ID of the package. This information is retrieved via CPUID
-    and deduced from the APIC IDs of the cores in the package.
-
-  - cpuinfo_x86.logical_id:
-
-    The logical ID of the package. As we do not trust BIOSes to enumerate the
-    packages in a consistent way, we introduced the concept of logical package
-    ID so we can sanely calculate the number of maximum possible packages in
-    the system and have the packages enumerated linearly.
-
-  - topology_max_packages():
-
-    The maximum possible number of packages in the system. Helpful for per
-    package facilities to preallocate per package information.
-
-  - cpu_llc_id:
-
-    A per-CPU variable containing:
-    - On Intel, the first APIC ID of the list of CPUs sharing the Last Level
-    Cache
-
-    - On AMD, the Node ID or Core Complex ID containing the Last Level
-    Cache. In general, it is a number identifying an LLC uniquely on the
-    system.
-
-* Cores:
-
-  A core consists of 1 or more threads. It does not matter whether the threads
-  are SMT- or CMT-type threads.
-
-  AMDs nomenclature for a CMT core is "Compute Unit". The kernel always uses
-  "core".
-
-  Core-related topology information in the kernel:
-
-  - smp_num_siblings:
-
-    The number of threads in a core. The number of threads in a package can be
-    calculated by:
-
-	threads_per_package = cpuinfo_x86.x86_max_cores * smp_num_siblings
-
-
-* Threads:
-
-  A thread is a single scheduling unit. It's the equivalent to a logical Linux
-  CPU.
-
-  AMDs nomenclature for CMT threads is "Compute Unit Core". The kernel always
-  uses "thread".
-
-  Thread-related topology information in the kernel:
-
-  - topology_core_cpumask():
-
-    The cpumask contains all online threads in the package to which a thread
-    belongs.
-
-    The number of online threads is also printed in /proc/cpuinfo "siblings."
-
-  - topology_sibling_cpumask():
-
-    The cpumask contains all online threads in the core to which a thread
-    belongs.
-
-   - topology_logical_package_id():
-
-    The logical package ID to which a thread belongs.
-
-   - topology_physical_package_id():
-
-    The physical package ID to which a thread belongs.
-
-   - topology_core_id();
-
-    The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
-    "core_id."
-
-
-
-System topology examples
-
-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
-
-   [package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
-
-2) Single Package, Dual 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
-
-	[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:
-
-	[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:
-
-	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
-				     -> [Compute Unit Core 1] -> Linux CPU 1
-		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
-				     -> [Compute Unit Core 1] -> Linux CPU 3
-
-4) Dual Package, Dual Core
-
-   a) One thread per core
-
-	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
-		    -> [core 1] -> [thread 0] -> Linux CPU 1
-
-	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
-		    -> [core 1] -> [thread 0] -> Linux CPU 3
-
-   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
-
-	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 4
-				-> [thread 1] -> Linux CPU 5
-		    -> [core 1] -> [thread 0] -> Linux CPU 6
-				-> [thread 1] -> Linux CPU 7
-
-      Alternative enumeration:
-
-	[package 0] -> [core 0] -> [thread 0] -> Linux CPU 0
-				-> [thread 1] -> Linux CPU 4
-		    -> [core 1] -> [thread 0] -> Linux CPU 1
-				-> [thread 1] -> Linux CPU 5
-
-	[package 1] -> [core 0] -> [thread 0] -> Linux CPU 2
-				-> [thread 1] -> Linux CPU 6
-		    -> [core 1] -> [thread 0] -> Linux CPU 3
-				-> [thread 1] -> Linux CPU 7
-
-      AMD nomenclature for CMT systems:
-
-	[node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0
-				     -> [Compute Unit Core 1] -> Linux CPU 1
-		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2
-				     -> [Compute Unit Core 1] -> Linux CPU 3
-
-	[node 1] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 4
-				     -> [Compute Unit Core 1] -> Linux CPU 5
-		 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 6
-				     -> [Compute Unit Core 1] -> Linux CPU 7
-- 
2.20.1