linux-kernel - Re: [PATCH v11 00/13] Add support for AMD hardware feedback interface

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Message-ID: <df4c0c3e-19b5-4521-9b9b-d445d65ee2c7@kernel.org>
Date: Mon, 23 Jun 2025 16:53:02 -0500
From: Mario Limonciello <superm1@...nel.org>
To: Mario Limonciello <superm1@...nel.org>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>
Cc: Perry Yuan <perry.yuan@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
 "H . Peter Anvin" <hpa@...or.com>, Jonathan Corbet <corbet@....net>,
 Huang Rui <ray.huang@....com>, "Gautham R . Shenoy"
 <gautham.shenoy@....com>, "Rafael J . Wysocki" <rafael@...nel.org>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 "open list:AMD HETERO CORE HARDWARE FEEDBACK DRIVER"
 <platform-driver-x86@...r.kernel.org>,
 "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
 <linux-kernel@...r.kernel.org>,
 "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
 "open list:AMD PSTATE DRIVER" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v11 00/13] Add support for AMD hardware feedback interface

On 6/9/2025 3:05 PM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> The AMD Heterogeneous core design and Hardware Feedback Interface (HFI)
> provide behavioral classification of 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 intended to be used to inform the scheduler
> of where the thread should be placed for optimal performance or energy efficiency.
> 
> The thread classification can be used to helps to select CPU from a ranking table
> that describes an efficiency and performance ranking for each classification from
> two dimensions. This is not currently done in this series, but is intended for future
> follow ups after the plumbing is laid down.
> 
> 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/
> 
> v10->v11:
>   * rebase on v6.16-rc1
>   * Adjust for Randy's and Ingo's feedback
> 
> Mario Limonciello (5):
>    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
>    platform/x86/amd: hfi: Add debugfs support
>    x86/itmt: Add debugfs file to show core priorities
> 
> Perry Yuan (8):
>    Documentation: x86: Add AMD Hardware Feedback Interface documentation
>    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/process: Clear hardware feedback history for AMD processors
> 
>   Documentation/arch/x86/amd-hfi.rst    | 133 +++++++
>   Documentation/arch/x86/index.rst      |   1 +
>   MAINTAINERS                           |   9 +
>   arch/x86/include/asm/msr-index.h      |   5 +
>   arch/x86/kernel/itmt.c                |  23 ++
>   arch/x86/kernel/process_64.c          |   4 +
>   drivers/cpufreq/amd-pstate.c          |   6 +
>   drivers/platform/x86/amd/Kconfig      |   1 +
>   drivers/platform/x86/amd/Makefile     |   1 +
>   drivers/platform/x86/amd/hfi/Kconfig  |  18 +
>   drivers/platform/x86/amd/hfi/Makefile |   7 +
>   drivers/platform/x86/amd/hfi/hfi.c    | 551 ++++++++++++++++++++++++++
>   12 files changed, 759 insertions(+)
>   create mode 100644 Documentation/arch/x86/amd-hfi.rst
>   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
> 

Ping on this series, thanks.