Messages in this thread | | | Date | Fri, 7 Jul 2023 13:28:05 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/cpu: Add support for modern x86-64-v* march |
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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
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