The AMD Heterogeneous core design and Hardware Feedback Interface (HFI)
provide behavioral classification and a dynamically updated ranking table
for the scheduler to use when choosing cores for tasks.

Threads are classified during runtime into enumerated classes.
Currently, the driver supports 3 classes (0 through 2). These classes
represent thread performance/power characteristics that may benefit from
special scheduling behaviors. The real-time thread classification is
consumed by the operating system and is used to inform the scheduler of
where the thread should be placed for optimal performance or energy efficiency.

The thread classification helps to select CPU from a ranking table that describes
an efficiency and performance ranking for each classification from two dimensions.

The ranking data provided by the ranking table are numbers ranging from 0 to 255,
where a higher performance value indicates higher performance capability and a higher
efficiency value indicates greater efficiency. All the CPU cores are ranked into
different class IDs. Within each class ranking, the cores may have different ranking
values. Therefore, picking from each classification ID will later allow the scheduler
to select the best core while threads are classified into the specified workload class.

This series was originally submitted by Perry Yuan [1] but he is now doing a different
role and he asked me to take over.

Link: https://lore.kernel.org/all/cover.1724748733.git.perry.yuan@amd.com/

On applicable hardware this series has between a 2% and 5% improvement across various
benchmarks.

There is however a cost associated with clearing history on the process context switch.
On average it increases the delay by 119ns, and also has a wider range in delays
(the standard deviation is 25% greater).

Mario Limonciello (3):
  MAINTAINERS: Add maintainer entry for AMD Hardware Feedback Driver
  cpufreq/amd-pstate: Disable preferred cores on designs with workload
    classification
  platform/x86/amd: hfi: Set ITMT priority from ranking data

Perry Yuan (10):
  Documentation: x86: Add AMD Hardware Feedback Interface documentation
  x86/cpufeatures: add X86_FEATURE_WORKLOAD_CLASS feature bit
  x86/msr-index: define AMD heterogeneous CPU related MSR
  platform/x86: hfi: Introduce AMD Hardware Feedback Interface Driver
  platform/x86: hfi: parse CPU core ranking data from shared memory
  platform/x86: hfi: init per-cpu scores for each class
  platform/x86: hfi: add online and offline callback support
  platform/x86: hfi: add power management callback
  x86/cpu: Enable SD_ASYM_PACKING for DIE Domain on AMD Processors
  x86/process: Clear hardware feedback history for AMD processors

 Documentation/arch/x86/amd-hfi.rst    | 116 ++++++
 Documentation/arch/x86/index.rst      |   1 +
 MAINTAINERS                           |   9 +
 arch/x86/include/asm/cpufeatures.h    |   1 +
 arch/x86/include/asm/hreset.h         |   6 +
 arch/x86/include/asm/msr-index.h      |   5 +
 arch/x86/kernel/cpu/common.c          |  15 +
 arch/x86/kernel/cpu/scattered.c       |   1 +
 arch/x86/kernel/process_32.c          |   3 +
 arch/x86/kernel/process_64.c          |   3 +
 arch/x86/kernel/smpboot.c             |   5 +-
 drivers/cpufreq/amd-pstate.c          |   4 +
 drivers/platform/x86/amd/Kconfig      |   1 +
 drivers/platform/x86/amd/Makefile     |   1 +
 drivers/platform/x86/amd/hfi/Kconfig  |  21 +
 drivers/platform/x86/amd/hfi/Makefile |   7 +
 drivers/platform/x86/amd/hfi/hfi.c    | 541 ++++++++++++++++++++++++++
 17 files changed, 738 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/arch/x86/amd-hfi.rst
 create mode 100644 arch/x86/include/asm/hreset.h
 create mode 100644 drivers/platform/x86/amd/hfi/Kconfig
 create mode 100644 drivers/platform/x86/amd/hfi/Makefile
 create mode 100644 drivers/platform/x86/amd/hfi/hfi.c

-- 
2.43.0

On Thu, Oct 10, 2024 at 02:36:52PM -0500, Mario Limonciello wrote:
> The AMD Heterogeneous core design and Hardware Feedback Interface (HFI)
> provide behavioral classification and a dynamically updated ranking table
> for the scheduler to use when choosing cores for tasks.
> 
> Threads are classified during runtime into enumerated classes.
> Currently, the driver supports 3 classes (0 through 2). These classes
> represent thread performance/power characteristics that may benefit from
> special scheduling behaviors. The real-time thread classification is
> consumed by the operating system and is used to inform the scheduler of
> where the thread should be placed for optimal performance or energy efficiency.
> 
> The thread classification helps to select CPU from a ranking table that describes
> an efficiency and performance ranking for each classification from two dimensions.
> 
> The ranking data provided by the ranking table are numbers ranging from 0 to 255,
> where a higher performance value indicates higher performance capability and a higher
> efficiency value indicates greater efficiency. All the CPU cores are ranked into
> different class IDs. Within each class ranking, the cores may have different ranking
> values. Therefore, picking from each classification ID will later allow the scheduler
> to select the best core while threads are classified into the specified workload class.
> 
> This series was originally submitted by Perry Yuan [1] but he is now doing a different
> role and he asked me to take over.

Sorry but can you specify the base commit/tree of this series? I can't apply
it on top of current platform-drivers-x86.git, though.

Confused...

-- 
An old man doll... just what I always wanted! - Clara

On 10/10/2024 19:54, Bagas Sanjaya wrote:
> On Thu, Oct 10, 2024 at 02:36:52PM -0500, Mario Limonciello wrote:
>> The AMD Heterogeneous core design and Hardware Feedback Interface (HFI)
>> provide behavioral classification and a dynamically updated ranking table
>> for the scheduler to use when choosing cores for tasks.
>>
>> Threads are classified during runtime into enumerated classes.
>> Currently, the driver supports 3 classes (0 through 2). These classes
>> represent thread performance/power characteristics that may benefit from
>> special scheduling behaviors. The real-time thread classification is
>> consumed by the operating system and is used to inform the scheduler of
>> where the thread should be placed for optimal performance or energy efficiency.
>>
>> The thread classification helps to select CPU from a ranking table that describes
>> an efficiency and performance ranking for each classification from two dimensions.
>>
>> The ranking data provided by the ranking table are numbers ranging from 0 to 255,
>> where a higher performance value indicates higher performance capability and a higher
>> efficiency value indicates greater efficiency. All the CPU cores are ranked into
>> different class IDs. Within each class ranking, the cores may have different ranking
>> values. Therefore, picking from each classification ID will later allow the scheduler
>> to select the best core while threads are classified into the specified workload class.
>>
>> This series was originally submitted by Perry Yuan [1] but he is now doing a different
>> role and he asked me to take over.
> 
> Sorry but can you specify the base commit/tree of this series? I can't apply
> it on top of current platform-drivers-x86.git, though.
> 
> Confused...
> 

Sorry about that.  As it crosses a few subsystems it will require some 
coordination to properly land once it has review comments.

It's (currently) based off:
https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/log/?h=linux-next

commit 57533bc760ae ("cpufreq/amd-pstate: Fix non kerneldoc comment")

On Thu, Oct 10, 2024 at 08:29:47PM -0500, Mario Limonciello wrote:
> On 10/10/2024 19:54, Bagas Sanjaya wrote:
> > On Thu, Oct 10, 2024 at 02:36:52PM -0500, Mario Limonciello wrote:
> > > The AMD Heterogeneous core design and Hardware Feedback Interface (HFI)
> > > provide behavioral classification and a dynamically updated ranking table
> > > for the scheduler to use when choosing cores for tasks.
> > > 
> > > Threads are classified during runtime into enumerated classes.
> > > Currently, the driver supports 3 classes (0 through 2). These classes
> > > represent thread performance/power characteristics that may benefit from
> > > special scheduling behaviors. The real-time thread classification is
> > > consumed by the operating system and is used to inform the scheduler of
> > > where the thread should be placed for optimal performance or energy efficiency.
> > > 
> > > The thread classification helps to select CPU from a ranking table that describes
> > > an efficiency and performance ranking for each classification from two dimensions.
> > > 
> > > The ranking data provided by the ranking table are numbers ranging from 0 to 255,
> > > where a higher performance value indicates higher performance capability and a higher
> > > efficiency value indicates greater efficiency. All the CPU cores are ranked into
> > > different class IDs. Within each class ranking, the cores may have different ranking
> > > values. Therefore, picking from each classification ID will later allow the scheduler
> > > to select the best core while threads are classified into the specified workload class.
> > > 
> > > This series was originally submitted by Perry Yuan [1] but he is now doing a different
> > > role and he asked me to take over.
> > 
> > Sorry but can you specify the base commit/tree of this series? I can't apply
> > it on top of current platform-drivers-x86.git, though.
> > 
> > Confused...
> > 
> 
> Sorry about that.  As it crosses a few subsystems it will require some
> coordination to properly land once it has review comments.
> 
> It's (currently) based off:
> https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/log/?h=linux-next
> 
> commit 57533bc760ae ("cpufreq/amd-pstate: Fix non kerneldoc comment")

Series successfully applied for review, thanks!

-- 
An old man doll... just what I always wanted! - Clara