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: <20241203215454.GJZ09-LmEWPZ502B7R@fat_crate.local>
Date: Tue, 3 Dec 2024 22:54:54 +0100
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>,
	"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

On Tue, Dec 03, 2024 at 02:11:29PM -0600, 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) {

You're going to call this on *every* AMD and on Hygon?

So that whole effort with X86_FEATURE_s was for nothing?

What's up?

-- 
Regards/Gruss,
    Boris.

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