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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Meng Li <li.meng@amd.com>, Borislav Petkov <bpetkov@amd.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Huang Rui <ray.huang@amd.com>,
	 linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	x86@kernel.org,  linux-acpi@vger.kernel.org,
	Shuah Khan <skhan@linuxfoundation.org>,
	 linux-kselftest@vger.kernel.org,
	Nathan Fontenot <nathan.fontenot@amd.com>,
	 Deepak Sharma <deepak.sharma@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	 Mario Limonciello <mario.limonciello@amd.com>,
	Shimmer Huang <shimmer.huang@amd.com>,
	 Perry Yuan <Perry.Yuan@amd.com>,
	Xiaojian Du <Xiaojian.Du@amd.com>,
	 Viresh Kumar <viresh.kumar@linaro.org>,
	Borislav Petkov <bp@alien8.de>,
	 Oleksandr Natalenko <oleksandr@natalenko.name>
Subject: Re: [PATCH V14 0/7] amd-pstate preferred core
Date: Mon, 29 Jan 2024 16:18:02 +0100	[thread overview]
Message-ID: <CAJZ5v0gzKdjZJBypEw1+czGN-SHbx0s0-h=Lq96+MDVAO11PYQ@mail.gmail.com> (raw)
In-Reply-To: <20240119090502.3869695-1-li.meng@amd.com>

On Fri, Jan 19, 2024 at 10:05 AM Meng Li <li.meng@amd.com> wrote:
>
> Hi all:
>
> The core frequency is subjected to the process variation in semiconductors.
> Not all cores are able to reach the maximum frequency respecting the
> infrastructure limits. Consequently, AMD has redefined the concept of
> maximum frequency of a part. This means that a fraction of cores can reach
> maximum frequency. To find the best process scheduling policy for a given
> scenario, OS needs to know the core ordering informed by the platform through
> highest performance capability register of the CPPC interface.
>
> Earlier implementations of amd-pstate preferred core only support a static
> core ranking and targeted performance. Now it has the ability to dynamically
> change the preferred core based on the workload and platform conditions and
> accounting for thermals and aging.
>
> Amd-pstate driver utilizes the functions and data structures provided by
> the ITMT architecture to enable the scheduler to favor scheduling on cores
> which can be get a higher frequency with lower voltage.
> We call it amd-pstate preferred core.
>
> Here sched_set_itmt_core_prio() is called to set priorities and
> sched_set_itmt_support() is called to enable ITMT feature.
> Amd-pstate driver uses the highest performance value to indicate
> the priority of CPU. The higher value has a higher priority.
>
> Amd-pstate driver will provide an initial core ordering at boot time.
> It relies on the CPPC interface to communicate the core ranking to the
> operating system and scheduler to make sure that OS is choosing the cores
> with highest performance firstly for scheduling the process. When amd-pstate
> driver receives a message with the highest performance change, it will
> update the core ranking.

Hi Boris,

You've had comments on the previous version of this.

Have they all been addressed?

  parent reply	other threads:[~2024-01-29 15:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-19  9:04 [PATCH V14 0/7] amd-pstate preferred core Meng Li
2024-01-19  9:04 ` [PATCH V14 1/7] x86: Drop CPU_SUP_INTEL from SCHED_MC_PRIO for the expansion Meng Li
2024-01-19  9:04 ` [PATCH V14 2/7] ACPI: CPPC: Add get the highest performance cppc control Meng Li
2024-01-19  9:04 ` [PATCH V14 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred core supporting Meng Li
2024-01-19  9:04 ` [PATCH V14 4/7] cpufreq: Add a notification message that the highest perf has changed Meng Li
2024-01-19  9:05 ` [PATCH V14 5/7] cpufreq: amd-pstate: Update amd-pstate preferred core ranking dynamically Meng Li
2024-01-19  9:05 ` [PATCH V14 6/7] Documentation: amd-pstate: introduce amd-pstate preferred core Meng Li
2024-01-19  9:05 ` [PATCH V14 7/7] Documentation: introduce amd-pstate preferrd core mode kernel command line options Meng Li
2024-01-29 15:18 ` Rafael J. Wysocki [this message]
2024-01-29 15:33   ` [PATCH V14 0/7] amd-pstate preferred core Borislav Petkov
2024-01-31 13:58     ` Rafael J. Wysocki
2024-02-18 16:10       ` Lucas Lee Jing Yi
2024-02-18 16:10         ` [PATCH] [PATCH] amd_pstate: fix erroneous highest_perf value on some CPUs Lucas Lee Jing Yi
2024-02-20  7:23           ` Meng, Li (Jassmine)
2024-02-20  9:02           ` Oleksandr Natalenko
2024-02-21 17:19             ` Lucas Lee Jing Yi
2024-02-21 17:19               ` Lucas Lee Jing Yi
2024-02-21 18:47                 ` Mario Limonciello
2024-02-19  1:02         ` [PATCH V14 0/7] amd-pstate preferred core Meng, Li (Jassmine)

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