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Tue, 23 Apr 2019 09:36:49 -0700 (PDT) Received: from localhost.localdomain ([104.238.181.70]) by smtp.gmail.com with ESMTPSA id v1sm24364801pff.81.2019.04.23.09.36.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Apr 2019 09:36:48 -0700 (PDT) From: Changbin Du To: Jonathan Corbet Subject: [PATCH v4 39/63] Documentation: x86: convert topology.txt to reST Date: Wed, 24 Apr 2019 00:29:08 +0800 Message-Id: <20190423162932.21428-40-changbin.du@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190423162932.21428-1-changbin.du@gmail.com> References: <20190423162932.21428-1-changbin.du@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Wed, 24 Apr 2019 05:41:32 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fenghua.yu@intel.com, mchehab+samsung@kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, linux-gpio@vger.kernel.org, x86@kernel.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, mingo@redhat.com, Bjorn Helgaas , tglx@linutronix.de, linuxppc-dev@lists.ozlabs.org, Changbin Du Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 --- 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 and Borislav Petkov . + +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 and Borislav Petkov . - -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