docs: ABI: drop two duplicate symbols

As warned by get_abi.py, there are two symbols that are
defined twice:

WARNING: /sys/devices/system/cpu/cpuX/topology/physical_package_id is defined 2 times: \

docs: ABI: drop two duplicate symbols

As warned by get_abi.py, there are two symbols that are
defined 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:70
WARNING: /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:70

As the documentation at testing/sysfs-devices-system-cpu, drop
the duplicated one from stable.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Link: https://lore.kernel.org/r/c3dce809f577584cf9aedafc6c2a0d5a9ca909ac.1739394480.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <[email protected]>

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topology/sysfs: Add PPIN in sysfs under cpu topology

PPIN is the Protected Processor Identification Number.
This is used to identify the socket as a Field Replaceable Unit (FRU).

Existing code only

topology/sysfs: Add PPIN in sysfs under cpu topology

PPIN 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 makes
it inconvenient for large clusters to use it for its intended purpose
of inventory control.

Add ppin to /sys/devices/system/cpu/cpu*/topology to make what
is already available using RDMSR more easily accessible. Make
the file read only for root in case there are still people
concerned about making a unique system "serial number" available.

Signed-off-by: Tony Luck <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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topology: Represent clusters of CPUs within a die

Both ACPI and DT provide the ability to describe additional layers of
topology between that of individual cores and higher level constructs
such as

topology: Represent clusters of CPUs within a die

Both ACPI and DT provide the ability to describe additional layers of
topology between that of individual cores and higher level constructs
such as the level at which the last level cache is shared.
In ACPI this can be represented in PPTT as a Processor Hierarchy
Node Structure [1] that is the parent of the CPU cores and in turn
has a parent Processor Hierarchy Nodes Structure representing
a higher level of topology.

For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
cluster has 4 cpus. All clusters share L3 cache data, but each cluster
has local L3 tag. On the other hand, each clusters will share some
internal 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 bandwidth
while packing tasks within one cluster will lead to smaller cache
synchronization latency. So both kernel and userspace will have
a chance to leverage this topology to deploy tasks accordingly to
achieve either smaller cache latency within one cluster or an even
distribution 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 related
sysfs attributes. PoC of HWLOC support at [2].

Note this patch only handle the ACPI case.

Special consideration is needed for SMT processors, where it is
necessary 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 identifying
a die level in the topology but that may be unrelate to the cluster
level.

[1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node
structure (Type 0)
[2] https://github.com/hisilicon/hwloc/tree/linux-cluster

Signed-off-by: Jonathan Cameron <[email protected]>
Signed-off-by: Tian Tao <[email protected]>
Signed-off-by: Barry Song <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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docs: cputopology: move the sysfs ABI description to right place

Documentation/admin-guide/cputopology.rst is the wrong place to describe
sysfs ABI. So move the cputopology ABI things to
Documentati

docs: cputopology: move the sysfs ABI description to right place

Documentation/admin-guide/cputopology.rst is the wrong place to describe
sysfs ABI. So move the cputopology ABI things to
Documentation/ABI/stable/sysfs-devices-system-cpu and add a reference to
ABI doc in Documentation/admin-guide/cputopology.rst.

Link: https://lkml.kernel.org/r/[email protected]
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Tian Tao <[email protected]>
Signed-off-by: Barry Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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powerpc: Document sysfs DSCR interface

Add some documentation about ...

/sys/devices/system/cpu/dscr_default
/sys/devices/system/cpu/cpuN/dscr

... to Documentation/ABI/stable.

Signed-off-by: Sam

powerpc: Document sysfs DSCR interface

Add some documentation about ...

/sys/devices/system/cpu/dscr_default
/sys/devices/system/cpu/cpuN/dscr

... to Documentation/ABI/stable.

Signed-off-by: Sam Bobroff <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>

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