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authorKevin Hilman <khilman@baylibre.com>2016-04-22 09:45:53 -0700
committerKevin Hilman <khilman@baylibre.com>2016-04-22 09:45:53 -0700
commitc0e309138be2e4ba1551dde76f7fa2479cd9198d (patch)
tree81d7681547f8717c5a5416315110050f1a2a4962 /Documentation
parent2193a3fd7bc6ffd607c1a791d05d22a4a2282c57 (diff)
parent3d51ae172d759198b2e47e104c31a92d20d17927 (diff)
downloadleg-kernel-c0e309138be2e4ba1551dde76f7fa2479cd9198d.tar.gz
Merge tag 'omap-for-v4.6/fixes-rc2-v2-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes
Merge "omap fixes against v4.6-rc2" from Tony Lindgren Fixes for omaps against v4.6-rc2, mostly to fix suspend for beagle-x15 that broke when we added runtime based SoC revision detection earlier. It seems suspend worked earlier as things were only partially initialized, while now we initialize things properly for dra7. Note that the "ARM: OMAP: Catch callers of revision information prior to it being populated" had to be reverted as it caused bogus warnings for other SoCs because omap initcalls bail out based on revision being set to 0 for other SoCs. These initcalls will mostly just disappear when we drop support for omap3 legacy booting. Also included is a fix for dra7 sys_32k_ck clock source that is not enabled on boot making system fall back to using emulated clock. * tag 'omap-for-v4.6/fixes-rc2-v2-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap: (198 commits) Revert "ARM: OMAP: Catch callers of revision information prior to it being populated" ARM: OMAP: Catch callers of revision information prior to it being populated ARM: dts: dra7: Correct clock tree for sys_32k_ck ARM: OMAP: DRA7: Provide proper class to omap2_set_globals_tap ARM: OMAP: DRA7: wakeupgen: Skip SAR save for wakeupgen Linux 4.6-rc2 v4l2-mc: avoid warning about unused variable Convert straggling drivers to new six-argument get_user_pages() .mailmap: add Christophe Ricard Make CONFIG_FHANDLE default y mm/page_isolation.c: fix the function comments oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head mm/page_isolation: fix tracepoint to mirror check function behavior mm/rmap: batched invalidations should use existing api x86/mm: TLB_REMOTE_SEND_IPI should count pages mm: fix invalid node in alloc_migrate_target() include/linux/huge_mm.h: return NULL instead of false for pmd_trans_huge_lock() mm, kasan: fix compilation for CONFIG_SLAB MAINTAINERS: orangefs mailing list is subscribers-only net: mvneta: fix changing MTU when using per-cpu processing ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/networking/switchdev.txt2
-rw-r--r--Documentation/x86/topology.txt208
2 files changed, 209 insertions, 1 deletions
diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt
index fad63136ee3e..2f659129694b 100644
--- a/Documentation/networking/switchdev.txt
+++ b/Documentation/networking/switchdev.txt
@@ -386,7 +386,7 @@ used. First phase is to "prepare" anything needed, including various checks,
memory allocation, etc. The goal is to handle the stuff that is not unlikely
to fail here. The second phase is to "commit" the actual changes.
-Switchdev provides an inftrastructure for sharing items (for example memory
+Switchdev provides an infrastructure for sharing items (for example memory
allocations) between the two phases.
The object created by a driver in "prepare" phase and it is queued up by:
diff --git a/Documentation/x86/topology.txt b/Documentation/x86/topology.txt
new file mode 100644
index 000000000000..06afac252f5b
--- /dev/null
+++ b/Documentation/x86/topology.txt
@@ -0,0 +1,208 @@
+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@linutronix.de> and Borislav Petkov <bp@alien8.de>.
+
+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.
+
+
+* 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_mask():
+
+ 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