linux-kernel - Re: [PATCH v2] x86/cpu: Enable SD_ASYM_PACKING for PKG domain on systems with AMD preferred cores

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Message-ID: <87d916f7-b9f5-4bae-82fe-6249e8647a62@cachyos.org>
Date: Tue, 3 Dec 2024 21:33:02 +0100
From: Peter Jung <ptr1337@...hyos.org>
To: Mario Limonciello <mario.limonciello@....com>,
 Borislav Petkov <bp@...en8.de>
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>,
 "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/cpu: Enable SD_ASYM_PACKING for PKG domain on
 systems with AMD preferred cores

This does fix the preferred core behavior now and it works now as it should.
Tested with a 9950X on several games, and the scheduler now picks the 
correct cores, which results into a heavy performance improvement, due 
not migrating through the second ccd.

Thanks!

Tested-by: Peter Jung <ptr1337@...hyos.org>

On 03.12.24 21:11, Mario Limonciello wrote:
> For the scheduler to use and prefer AMD preferred core rankings set
> SD_ASYM_PACKING for x86_die_flags().
> 
> Signed-off-by: Mario Limonciello<mario.limonciello@....com>
> ---
> v2:
>   * Fix c23 compatibility issue reported by LKP
> ---
>   arch/x86/kernel/smpboot.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index b5a8f0891135b..6a38cf3feb1a9 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -62,6 +62,8 @@
>   #include <linux/mc146818rtc.h>
>   #include <linux/acpi.h>
>   
> +#include <acpi/cppc_acpi.h>
> +
>   #include <asm/acpi.h>
>   #include <asm/cacheinfo.h>
>   #include <asm/desc.h>
> @@ -501,6 +503,15 @@ static int x86_die_flags(void)
>   	    cpu_feature_enabled(X86_FEATURE_AMD_HETEROGENEOUS_CORES))
>   		return x86_sched_itmt_flags();
>   
> +	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
> +	    boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
> +		bool prefcore = false;
> +
> +		amd_detect_prefcore(&prefcore);
> +		if (prefcore)
> +			return x86_sched_itmt_flags();
> +	}
> +
>   	return 0;
>   }
>   
> 
> base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
> -- 2.43.0
>