[PATCH v4 00/13] x86/resctrl: Support for AMD QoS new features and bug fix

Babu Moger
2022-09-07T18:00:07Z

New AMD processors can now support following QoS features.

1. Slow Memory Bandwidth Allocation (SMBA)
With this feature, the QOS enforcement policies can be applied
to the external slow memory connected to the host. QOS enforcement
is accomplished by assigning a Class Of Service (COS) to a processor
and specifying allocations or limits for that COS for each resource
to be allocated.

Currently, CXL.memory is the only supported "slow" memory device. With
the support of SMBA feature the hardware enables bandwidth allocation
on the slow memory devices.

2. Bandwidth Monitoring Event Configuration (BMEC)
The bandwidth monitoring events mbm_total_event and mbm_local_event
are set to count all the total and local reads/writes respectively.
With the introduction of slow memory, the two counters are not enough
to count all the different types are memory events. With the feature
BMEC, the users have the option to configure mbm_total_event and
mbm_local_event to count the specific type of events.

Following are the bitmaps of events supported.
Bits Description
6 Dirty Victims from the QOS domain to all types of memory
5 Reads to slow memory in the non-local NUMA domain
4 Reads to slow memory in the local NUMA domain
3 Non-temporal writes to non-local NUMA domain
2 Non-temporal writes to local NUMA domain
1 Reads to memory in the non-local NUMA domain
0 Reads to memory in the local NUMA domain

This series adds support for these features. Added a bug fix and a code cleanup.

Feature description is available in the specification, "AMD64 Technology Platform Quality
of Service Extensions, Revision: 1.03 Publication # 56375 Revision: 1.03 Issue Date: February 2022".

Link: https://www.amd.com/en/support/tech-docs/amd64-technology-platform-quality-service-extensions
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537

---
4:
Got numerios of comments from Reinette Chatre. Addressed most of them.
Summary of changes.
1. Removed mon_configurable under /sys/fs/resctrl/info/L3_MON/.
2. Updated mon_features texts if the BMEC is supported.
3. Added more explanation about the slow memory support.
4. Replaced smp_call_function_many with on_each_cpu_mask call.
5. Removed arch_has_empty_bitmaps
6. Few other text changes.
7. Removed Reviewed-by if the patch is modified.
8. Rebased the patches to latest tip.

v3:
https://lore.kernel.org/lkml/166117559756.6695.16047463526634290701.stgit@bmoger-ubuntu/
a. Rebased the patches to latest tip. Resolved some conflicts.
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
b. Taken care of feedback from Bagas Sanjaya.
c. Added Reviewed by from Mingo.
Note: I am still looking for comments from Reinette or Fenghua.

v2:
https://lore.kernel.org/lkml/165938717220.724959.10931629283087443782.stgit@bmoger-ubuntu/
a. Rebased the patches to latest stable tree (v5.18.15). Resolved some conflicts.
b. Added the patch to fix CBM issue on AMD. This was originally discussed
https://lore.kernel.org/lkml/20220517001234.3137157-1-eranian@google.com/

v1:
https://lore.kernel.org/lkml/165757543252.416408.13547339307237713464.stgit@bmoger-ubuntu/

Babu Moger (13):
x86/resctrl: Fix min_cbm_bits for AMD
x86/resctrl: Remove arch_has_empty_bitmaps
x86/cpufeatures: Add Slow Memory Bandwidth Allocation feature flag
x86/resctrl: Add a new resource type RDT_RESOURCE_SMBA
x86/cpufeatures: Add Bandwidth Monitoring Event Configuration feature flag
x86/resctrl: Include new features in command line options
x86/resctrl: Detect and configure Slow Memory Bandwidth allocation
x86/resctrl : Introduce data structure to support monitor configuration
x86/resctrl: Add sysfs interface files to read/write event configuration
x86/resctrl: Add the sysfs interface to read the event configuration
x86/resctrl: Add sysfs interface to write the event configuration
x86/resctrl: Replace smp_call_function_many with on_each_cpu_mask
Documentation/x86: Update resctrl_ui.rst for new features

.../admin-guide/kernel-parameters.txt | 2 +-
Documentation/x86/resctrl.rst | 148 +++++++++-
arch/x86/include/asm/cpufeatures.h | 2 +
arch/x86/kernel/cpu/resctrl/core.c | 58 +++-
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 5 +-
arch/x86/kernel/cpu/resctrl/internal.h | 32 ++-
arch/x86/kernel/cpu/resctrl/monitor.c | 9 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 272 +++++++++++++++---
arch/x86/kernel/cpu/scattered.c | 2 +
include/linux/resctrl.h | 6 +-
10 files changed, 479 insertions(+), 57 deletions(-)

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