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| author | Keith Busch <keith.busch@intel.com> | 2019-03-11 14:56:01 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-04 18:41:21 +0200 |
| commit | e1cf33aafb8462c7d0a0e6349925870316f040ee (patch) | |
| tree | a45159a6e1d29d976957ec619c57ee296c421a3a /Documentation/ABI/stable | |
| parent | 08d9dbe72b1f899468b2b34f9309e88a84f440f2 (diff) | |
node: Add heterogenous memory access attributes
Heterogeneous memory systems provide memory nodes with different latency
and bandwidth performance attributes. Provide a new kernel interface
for subsystems to register the attributes under the memory target
node's initiator access class. If the system provides this information,
applications may query these attributes when deciding which node to
request memory.
The following example shows the new sysfs hierarchy for a node exporting
performance attributes:
# tree -P "read*|write*"/sys/devices/system/node/nodeY/accessZ/initiators/
/sys/devices/system/node/nodeY/accessZ/initiators/
|-- read_bandwidth
|-- read_latency
|-- write_bandwidth
`-- write_latency
The bandwidth is exported as MB/s and latency is reported in
nanoseconds. The values are taken from the platform as reported by the
manufacturer.
Memory accesses from an initiator node that is not one of the memory's
access "Z" initiator nodes linked in the same directory may observe
different performance than reported here. When a subsystem makes use
of this interface, initiators of a different access number may not have
the same performance relative to initiators in other access numbers, or
omitted from the any access class' initiators.
Descriptions for memory access initiator performance access attributes
are added to sysfs stable documentation.
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI/stable')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-devices-node | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node index 433bcc04e542..735a40a3f9b2 100644 --- a/Documentation/ABI/stable/sysfs-devices-node +++ b/Documentation/ABI/stable/sysfs-devices-node @@ -114,3 +114,31 @@ Contact: Keith Busch <keith.busch@intel.com> Description: The directory containing symlinks to memory targets that this initiator node has class "Y" access. + +What: /sys/devices/system/node/nodeX/accessY/initiators/read_bandwidth +Date: December 2018 +Contact: Keith Busch <keith.busch@intel.com> +Description: + This node's read bandwidth in MB/s when accessed from + nodes found in this access class's linked initiators. + +What: /sys/devices/system/node/nodeX/accessY/initiators/read_latency +Date: December 2018 +Contact: Keith Busch <keith.busch@intel.com> +Description: + This node's read latency in nanoseconds when accessed + from nodes found in this access class's linked initiators. + +What: /sys/devices/system/node/nodeX/accessY/initiators/write_bandwidth +Date: December 2018 +Contact: Keith Busch <keith.busch@intel.com> +Description: + This node's write bandwidth in MB/s when accessed from + found in this access class's linked initiators. + +What: /sys/devices/system/node/nodeX/accessY/initiators/write_latency +Date: December 2018 +Contact: Keith Busch <keith.busch@intel.com> +Description: + This node's write latency in nanoseconds when access + from nodes found in this class's linked initiators. |