linux-kernel - Re: [PATCH v3 5/5] x86/amd: Use heterogeneous core topology for identifying boost numerator

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Message-ID: <20241025135107.GPZxuiS38_s3KWe8xj@fat_crate.local>
Date: Fri, 25 Oct 2024 15:51:07 +0200
From: Borislav Petkov <bp@...en8.de>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
	"H . Peter Anvin" <hpa@...or.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	"Gautham R . Shenoy" <gautham.shenoy@....com>,
	Perry Yuan <perry.yuan@....com>,
	Brijesh Singh <brijesh.singh@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	Li RongQing <lirongqing@...du.com>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <linux-kernel@...r.kernel.org>,
	"open list:ACPI" <linux-acpi@...r.kernel.org>,
	"open list:AMD PSTATE DRIVER" <linux-pm@...r.kernel.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Subject: Re: [PATCH v3 5/5] x86/amd: Use heterogeneous core topology for
 identifying boost numerator

On Wed, Oct 23, 2024 at 12:43:57PM -0500, Mario Limonciello wrote:
>  int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
>  {
> +	enum x86_topology_cpu_type core_type = get_topology_generic_cpu_type(&cpu_data(cpu));
>  	bool prefcore;
>  	int ret;
> +	u32 tmp;
>  
>  	ret = amd_detect_prefcore(&prefcore);
>  	if (ret)
> @@ -261,6 +263,27 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
>  			break;
>  		}
>  	}
> +

What's the difference between this case:

> +	/* detect if running on heterogeneous design */
> +	switch (core_type) {
> +	case TOPO_CPU_TYPE_UNKNOWN:
	     ^^^^^^^^^^^^^^^^^^^^^^^

> +		break;
> +	case TOPO_CPU_TYPE_PERFORMANCE:
> +		/* use the max scale for performance cores */
> +		*numerator = CPPC_HIGHEST_PERF_PERFORMANCE;
> +		return 0;
> +	case TOPO_CPU_TYPE_EFFICIENCY:
> +		/* use the highest perf value for efficiency cores */
> +		ret = amd_get_highest_perf(cpu, &tmp);
> +		if (ret)
> +			return ret;
> +		*numerator = tmp;
> +		return 0;
> +	default:

... and this case and why aren't you warning if TOPO_CPU_TYPE_UNKNOWN?

I think for that you need to check X86_FEATURE_AMD_HETEROGENEOUS_CORES and
warn if set but still CPU type unknown or?

> +		pr_warn("WARNING: Undefined core type %d found\n", core_type);
> +		break;
> +	}

-- 
Regards/Gruss,
    Boris.

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