Changes in sysfs-devices-system-cpu

b09d96e0 - docs: ABI: drop two duplicate symbols

Wed, 12 Feb 2025 21:08:01 +0000

docs: ABI: drop two duplicate symbolsAs warned by get_abi.py, there are two symbols that aredefined twice:WARNING: /sys/devices/system/cpu/cpuX/topology/physical_package_id is defined 2 times: \ /new_devel/v4l/docs/Documentation/ABI/stable/sysfs-devices-system-cpu:27; \ /new_devel/v4l/docs/Documentation/ABI/testing/sysfs-devices-system-cpu:70WARNING: /sys/devices/system/cpu/cpuX/topology/ppin is defined 2 times: \ /new_devel/v4l/docs/Documentation/ABI/stable/sysfs-devices-system-cpu:89; \ /new_devel/v4l/docs/Documentation/ABI/testing/sysfs-devices-system-cpu:70As the documentation at testing/sysfs-devices-system-cpu, dropthe duplicated one from stable.Signed-off-by: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/c3dce809f577584cf9aedafc6c2a0d5a9ca909ac.1739394480.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/ABI/stable/sysfs-devices-system-cpu

ab28e944 - topology/sysfs: Add PPIN in sysfs under cpu topology

Mon, 31 Jan 2022 23:01:11 +0000

topology/sysfs: Add PPIN in sysfs under cpu topologyPPIN is the Protected Processor Identification Number.This is used to identify the socket as a Field Replaceable Unit (FRU).Existing code only displays this when reporting errors. But this makesit inconvenient for large clusters to use it for its intended purposeof inventory control.Add ppin to /sys/devices/system/cpu/cpu*/topology to make whatis already available using RDMSR more easily accessible. Makethe file read only for root in case there are still peopleconcerned about making a unique system "serial number" available.Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20220131230111.2004669-6-tony.luck@intel.com List of files: /linux-6.15/Documentation/ABI/stable/sysfs-devices-system-cpu

c5e22fef - topology: Represent clusters of CPUs within a die

Fri, 24 Sep 2021 08:51:02 +0000

topology: Represent clusters of CPUs within a dieBoth ACPI and DT provide the ability to describe additional layers oftopology between that of individual cores and higher level constructssuch as the level at which the last level cache is shared.In ACPI this can be represented in PPTT as a Processor HierarchyNode Structure [1] that is the parent of the CPU cores and in turnhas a parent Processor Hierarchy Nodes Structure representinga higher level of topology.For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and eachcluster has 4 cpus. All clusters share L3 cache data, but each clusterhas local L3 tag. On the other hand, each clusters will share someinternal system bus.+-----------------------------------+ +---------+| +------+ +------+ +--------------------------+ || | CPU0 | | cpu1 | | +-----------+ | || +------+ +------+ | | | | || +----+ L3 | | || +------+ +------+ cluster | | tag | | || | CPU2 | | CPU3 | | | | | || +------+ +------+ | +-----------+ | || | | |+-----------------------------------+ | |+-----------------------------------+ | || +------+ +------+ +--------------------------+ || | | | | | +-----------+ | || +------+ +------+ | | | | || | | L3 | | || +------+ +------+ +----+ tag | | || | | | | | | | | || +------+ +------+ | +-----------+ | || | | |+-----------------------------------+ | L3 | | data |+-----------------------------------+ | || +------+ +------+ | +-----------+ | || | | | | | | | | || +------+ +------+ +----+ L3 | | || | | tag | | || +------+ +------+ | | | | || | | | | | +-----------+ | || +------+ +------+ +--------------------------+ |+-----------------------------------| | |+-----------------------------------| | || +------+ +------+ +--------------------------+ || | | | | | +-----------+ | || +------+ +------+ | | | | || +----+ L3 | | || +------+ +------+ | | tag | | || | | | | | | | | || +------+ +------+ | +-----------+ | || | | |+-----------------------------------+ | |+-----------------------------------+ | || +------+ +------+ +--------------------------+ || | | | | | +-----------+ | || +------+ +------+ | | | | || | | L3 | | || +------+ +------+ +---+ tag | | || | | | | | | | | || +------+ +------+ | +-----------+ | || | | |+-----------------------------------+ | |+-----------------------------------+ | || +------+ +------+ +--------------------------+ || | | | | | +-----------+ | || +------+ +------+ | | | | || | | L3 | | || +------+ +------+ +--+ tag | | || | | | | | | | | || +------+ +------+ | +-----------+ | || | +---------++-----------------------------------+That means spreading tasks among clusters will bring more bandwidthwhile packing tasks within one cluster will lead to smaller cachesynchronization latency. So both kernel and userspace will havea chance to leverage this topology to deploy tasks accordingly toachieve either smaller cache latency within one cluster or an evendistribution of load among clusters for higher throughput.This patch exposes cluster topology to both kernel and userspace.Libraried like hwloc will know cluster by cluster_cpus and relatedsysfs attributes. PoC of HWLOC support at [2].Note this patch only handle the ACPI case.Special consideration is needed for SMT processors, where it isnecessary to move 2 levels up the hierarchy from the leaf nodes(thus skipping the processor core level).Note that arm64 / ACPI does not provide any means of identifyinga die level in the topology but that may be unrelate to the clusterlevel.[1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0)[2] https://github.com/hisilicon/hwloc/tree/linux-clusterSigned-off-by: Jonathan Cameron Signed-off-by: Tian Tao Signed-off-by: Barry Song Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com List of files: /linux-6.15/Documentation/ABI/stable/sysfs-devices-system-cpu

05a463ec - docs: cputopology: move the sysfs ABI description to right place

Fri, 11 Jun 2021 05:22:49 +0000

docs: cputopology: move the sysfs ABI description to right placeDocumentation/admin-guide/cputopology.rst is the wrong place to describesysfs ABI. So move the cputopology ABI things toDocumentation/ABI/stable/sysfs-devices-system-cpu and add a reference toABI doc in Documentation/admin-guide/cputopology.rst.Link: https://lkml.kernel.org/r/20210319041618.14316-1-song.bao.hua@hisilicon.comCc: Greg Kroah-Hartman Signed-off-by: Tian Tao Signed-off-by: Barry Song Link: https://lore.kernel.org/r/20210611052249.25776-1-song.bao.hua@hisilicon.comSigned-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/ABI/stable/sysfs-devices-system-cpu

26c88f93 - powerpc: Document sysfs DSCR interface

Wed, 21 May 2014 06:32:39 +0000

powerpc: Document sysfs DSCR interfaceAdd some documentation about .../sys/devices/system/cpu/dscr_default/sys/devices/system/cpu/cpuN/dscr... to Documentation/ABI/stable.Signed-off-by: Sam Bobroff Signed-off-by: Benjamin Herrenschmidt List of files: /linux-6.15/Documentation/ABI/stable/sysfs-devices-system-cpu