linux-kernel - Re: [PATCH v4 09/11] cpufreq: amd-pstate: implement heterogeneous core topology for highest performance initialization

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Date: Tue, 18 Jun 2024 23:23:48 +0200
From: Borislav Petkov <bp@...en8.de>
To: Perry Yuan <perry.yuan@....com>
Cc: rafael.j.wysocki@...el.com, Mario.Limonciello@....com,
	viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com,
	Alexander.Deucher@....com, Xinmei.Huang@....com,
	Xiaojian.Du@....com, Li.Meng@....com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 09/11] cpufreq: amd-pstate: implement heterogeneous
 core topology for highest performance initialization

On Mon, Jun 17, 2024 at 02:59:11PM +0800, Perry Yuan wrote:
> Introduces an optimization to the AMD-Pstate driver by implementing
> a heterogeneous core topology for the initialization of the highest
> performance value while driver loading.
> The two core types supported are "performance" and "efficiency".
> Each core type has different highest performance and frequency values
> configured by the platform.  The `amd_pstate` driver needs to identify
> the type of core to correctly set an appropriate highest perf value.
> 
> X86_FEATURE_HETERO_CORE_TOPOLOGY is used to identify whether the
> processor support heterogeneous core type by reading CPUID leaf
> Fn_0x80000026_EAX and bit 30. if the bit is set as one, then amd_pstate
> driver will check EBX 30:28 bits to get the core type.

There will be a special ->cpu_type member for that eventually:

https://lore.kernel.org/r/20240617-add-cpu-type-v1-1-b88998c01e76@linux.intel.com

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette