[PATCH v4 0/4] Add interfaces for ACPI MRRM table

Tony Luck
2025-04-29T20:24:18Z

Memory used to be homogeneous. Then NUMA came along. Later different
types of memory (persistent memory, on-package high bandwidth memory,
CXL attached memory).

Each type of memory has its own performance characteristics, and users
will need to monitor and control access by type.

The MRRM solution is to tag physical address ranges with "region IDs"
so that platform firmware[1] can indicate the type of memory for each
range (with separate tags available for local vs. remote access to
each range). Note that these ranges can include addresses reserved
for future hotplugged memory.

The region IDs will be used to provide separate event counts for each
region for "perf" and for the "resctrl" file system to monitor and
control memory bandwidth in each region.

Users will need to know the address range(s) that are part of each
region. This patch series adds
/sys/firmware/acpi/memory_ranges/rangeX
directories to provide user space accessible enumeration.

-Tony

[1] MRRM definition allow for future expansion for the OS to assign
these region IDs.

Changes since version 3 here:
https://lore.kernel.org/all/20250410223207.257722-1-tony.luck@intel.com/

1) Rebase to v6.15-rc4
2) Removed ugly #ifdef in acpi_mrrm.c with better fix for CONFIG_NUMA=n
3) Moved stub for acpi_mrrm_max_mem_region() into #else !ACPI section
of <linux/acpi.h>

Tony Luck (4):
ACPICA: Define MRRM ACPI table
ACPI/MRRM: Minimal parse of ACPI MRRM table
ACPI/MRRM: Add /sys files to describe memory ranges
ACPI: Add documentation for exposing MRRM data

include/linux/acpi.h | 9 +
include/acpi/actbl1.h | 7 +
include/acpi/actbl2.h | 42 ++++
drivers/acpi/acpi_mrrm.c | 183 ++++++++++++++++++
Documentation/ABI/testing/sysfs-firmware-acpi | 21 ++
arch/x86/Kconfig | 1 +
drivers/acpi/Kconfig | 3 +
drivers/acpi/Makefile | 1 +
8 files changed, 267 insertions(+)
create mode 100644 drivers/acpi/acpi_mrrm.c

base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
--
2.48.1