From: Borislav Petkov <bp@alien8.de>
To: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/cpu: Add support for modern x86-64-v* march
Date: Fri, 7 Jul 2023 13:28:05 +0200 [thread overview]
Message-ID: <20230707112805.GCZKf2xdf2kMJ/S1DU@fat_crate.local> (raw)
In-Reply-To: <20230707105601.133221-1-dimitri.ledkov@canonical.com>
On Fri, Jul 07, 2023 at 11:56:00AM +0100, Dimitri John Ledkov wrote:
> Add support for setting march to x86-64-v2, x86-64-v3, x86-64-v4 with
> tuning set to an early family of CPUs that support such instruction
> levels. By default gcc sets generic tuning for x86-64-v*, which is
> suboptimal for all brands of CPUs with such instruction set support.
Prove that it is suboptimal for the kernel. Numbers please.
And even if it shows on *some* uarch:
* we need a *single* setting for distro kernels - i.e.,
CONFIG_GENERIC_CPU and compilers do make sure that -mtune=generic does
the most optimal code generation for all uarches
* our Kconfig option set is abysmal so don't need any more if useless.
Yeah, a patch like that keeps popping up on a regular basis but no,
thanks.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-07-07 11:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 10:56 Dimitri John Ledkov
2023-07-07 11:28 ` Borislav Petkov [this message]
2023-07-07 11:46 ` Dimitri John Ledkov
2023-07-07 12:05 ` Borislav Petkov
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