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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 <Jonathan.Cameron@huawei.com>
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
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ACPI 6.4 adds a 'cache id' to the PPTT Cache Type Structure.
Copy this property across into the cacheinfo leaf when it was
provided by firmware.
This value gets exposed to userspace as:
/sys/devices/system/cpu/cpu*/cache/index*/id.
See the "Cache IDs" section of Documentation/x86/resctrl.rst.
Co-authored-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The fourth parameter 'level' of function 'acpi_find_cache_level()' is
a signed interger, but its caller 'acpi_find_cache_node()' passes that
parameter an unsigned interger.
Make the paramter type inconsistency go away.
Signed-off-by: Tian Tao <tiantao6@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
[ rjw: Subject/changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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ACPI 6.3 adds a flag to the CPU node to indicate whether
the given PE is a thread. Add a function to return that
information for a given linux logical CPU.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Robert Richter <rrichter@marvell.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Will Deacon <will@kernel.org>
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ACPI 6.3 adds a flag to indicate that child nodes are all
identical cores. This is useful to authoritatively determine
if a set of (possibly offline) cores are identical or not.
Since the flag doesn't give us a unique id we can generate
one and use it to create bitmaps of sibling nodes, or simply
in a loop to determine if a subset of cores are identical.
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
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The ACPI specification implies that the IDENTICAL flag should be
set on all non leaf nodes where the children are identical.
This means that we need to be searching for the last node with
the identical flag set rather than the first one.
Since this flag is also dependent on the table revision, we
need to add a bit of extra code to verify the table revision,
and the next node's state in the traversal. Since we want to
avoid function pointers here, lets just special case
the IDENTICAL flag.
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
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Fix some misspellings in comments. No functional change intended.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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ACPI 6.3 bumps the PPTT table revision and adds a LEAF_NODE flag.
This allows us to avoid a second pass through the table to assure
that the node in question is a leaf.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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For a system using ACPI-based FW without a PPTT, we may get many warnings
about the lack of a PPTT, as shown:
root@(none)$ dmesg | grep -i pptt
[ 0.010125] ACPI PPTT: No PPTT table found, cpu topology may be inaccurate
[ 7.138339] ACPI PPTT: No PPTT table found, cache topology may be inaccurate
[ 7.145368] ACPI PPTT: No PPTT table found, cache topology may be inaccurate
These logs are generated with pr_warn_once(), so the intention was for a
single log, but the logs overlap, so consolidate them.
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The type of a cache might not be specified by architectural mechanisms (ie
system registers), but its type might be specified in the PPTT. In this
case, we should populate the type of the cache, rather than leave it
undefined.
This fixes the issue where the cacheinfo driver will not populate sysfs
for such caches, resulting in the information missing from utilities like
lstopo and lscpu, thus degrading the user experience.
Fixes: 2bd00bcd73e5 (ACPI/PPTT: Add Processor Properties Topology Table parsing)
Reported-by: Vijaya Kumar K <vkilari@codeaurora.org>
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Currently, we use the ACPI processor ID only for the leaf/processor nodes
as the specification states it must match the value of the ACPI processor
ID field in the processor’s entry in the MADT.
However, if a PPTT structure represents a processors group, it
matches a processor container UID in the namespace and the
ACPI_PPTT_ACPI_PROCESSOR_ID_VALID flag indicates whether the
ACPI processor ID is valid.
Let's use UID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set to be
consistent instead of using table offset as it's currently done for
non-leaf nodes.
Fixes: 2bd00bcd73e5 (ACPI/PPTT: Add Processor Properties Topology Table parsing)
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Jeremy Linton <jeremy.linton@arm.com>
[ rjw: Changelog (minor) ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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ACPI 6.2 adds a new table, which describes how processing units
are related to each other in tree like fashion. Caches are
also sprinkled throughout the tree and describe the properties
of the caches in relation to other caches and processing units.
Add the code to parse the cache hierarchy and report the total
number of levels of cache for a given core using
acpi_find_last_cache_level() as well as fill out the individual
cores cache information with cache_setup_acpi() once the
cpu_cacheinfo structure has been populated by the arch specific
code.
An additional patch later in the set adds the ability to report
peers in the topology using find_acpi_cpu_topology()
to report a unique ID for each processing unit at a given level
in the tree. These unique id's can then be used to match related
processing units which exist as threads, within a given
package, etc.
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Vijaya Kumar K <vkilari@codeaurora.org>
Tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Tested-by: Tomasz Nowicki <Tomasz.Nowicki@cavium.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Jonathan Cameron
James Morse
Tian Tao
Jeremy Linton
Bjorn Helgaas
John Garry
Jeffrey Hugo
Sudeep Holla