[v3,0/3] cxl: Add support to report region access coordinates to numa nodes

Message

Dave Jiang Jan. 4, 2024, 11:48 p.m. UTC

v3:
- Make attributes not visible if no data. (Jonathan)
- Fix documentation verbiage. (Jonathan)
- Check against read bandwidth instead of write bandwidth due to future RO devices. (Jonathan)
- Export node_set_perf_attrs() to all namespaces. (Jonathan)
- Remove setting of coordinate access level 1. (Jonathan)

v2:
- Move calculation function to core/cdat.c due to QTG series changes
- Make cxlr->coord static (Dan)
- Move calculation to cxl_region_attach to be under cxl_dpa_rwsem (Dan)
- Normalize perf latency numbers to nanoseconds (Brice)
- Update documentation with units and initiator details (Brice, Dan)
- Fix notifier return values (Dan)
- Use devm_add_action_or_reset() to unregister memory notifier (Dan)

This series adds support for computing the performance data of a CXL region
and also updates the performance data to the NUMA node. The series depends on
the posted QTG ID support series [1].

CXL memory devices already attached before boot are enumerated by the BIOS.
The SRAT and HMAT tables are properly setup to including memory regions
enumerated from those CXL memory devices. For regions not programmed or a
hot-plugged CXL memory device, the BIOS does not have the relevant
information and the performance data has to be caluclated by the driver
post region assembly.

Recall from [1] that the performance data for the ranges of a CXL memory device
is computed and cached. A CXL memory region can be backed by one or more
devices. Thus the performance data would be the aggregated bandwidth of all
devices that back a region and the worst latency out of all devices backing
the region.

[1]: https://lore.kernel.org/linux-cxl/170248552797.801570.14580769385012396142.stgit@djiang5-mobl3/T/#t

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Dave Jiang (3):
      cxl/region: Calculate performance data for a region
      cxl/region: Add sysfs attribute for locality attributes of CXL regions
      cxl: Add memory hotplug notifier for cxl region


 Documentation/ABI/testing/sysfs-bus-cxl | 60 ++++++++++++++++++
 drivers/base/node.c                     |  1 +
 drivers/cxl/core/cdat.c                 | 53 ++++++++++++++++
 drivers/cxl/core/region.c               | 84 +++++++++++++++++++++++++
 drivers/cxl/cxl.h                       |  8 +++
 5 files changed, 206 insertions(+)

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