linux-kernel - Re: Lazy FPU restoration / moving kernel_fpu

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Message-ID: <CAHmME9pqANOxpKMujWoP_rydcZ-cDGaypLOs=kdXuB4pkdLw2A@mail.gmail.com>
Date:   Fri, 15 Jun 2018 22:48:39 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Andrew Lutomirski <luto@...nel.org>
Cc:     dave.hansen@...ux.intel.com, riel@...riel.com,
        LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>
Subject: Re: Lazy FPU restoration / moving kernel_fpu_end() to context switch

On Fri, Jun 15, 2018 at 10:27 PM Jason A. Donenfeld <Jason@...c4.com> wrote:
> AVX512 - Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz
> Inside: 634415672
> Outside: 286698960
> Percent speedup: 121

More realistic results, with turbo turned off:

Inside: 616851298
Outside: 339606790
Percent speedup: 81

Still a pretty outstanding speedup.