linux-kernel - Re: [regression 5.4.97 → 5.10.24]: raid6 avx2x4 speed drops from 18429 MB/s to 6155 MB/s

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Message-ID: <42011184-de0b-25d1-534f-a0d412d287a2@tmb.nu>
Date:   Sat, 03 Apr 2021 12:49:32 +0000
From:   Thomas Backlund <tmb@....nu>
To:     Borislav Petkov <bp@...en8.de>, Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        LKML <linux-kernel@...r.kernel.org>, Song Liu <song@...nel.org>,
        linux-raid@...r.kernel.org, it+linux-x86@...gen.mpg.de
Subject: Re: [regression 5.4.97 → 5.10.24]: raid6 avx2x4 speed drops from 18429 MB/s to 6155 MB/s

Den 2021-04-02 kl. 17:05, skrev Borislav Petkov:
> On Fri, Apr 02, 2021 at 10:33:51AM +0200, Paul Menzel wrote:
>> Dear Linux folks,
>>
>>
>> On an two socket AMD EPYC 7601, we noticed a decrease in raid6 avx2x4 speed
>> shown at the beginning of the boot.
>>
>>                         5.4.95        5.10.24
>> ----------------------------------------------
>> raid6: avx2x4 gen()   18429 MB/s     6155 MB/s
>> raid6: avx2x4 xor()    6644 MB/s     4274 MB/s
>> raid6: avx2x2 gen()   17894 MB/s    18744 MB/s
>> raid6: avx2x2 xor()   11642 MB/s    11950 MB/s
>> raid6: avx2x1 gen()   13992 MB/s    17112 MB/s
>> raid6: avx2x1 xor()   10855 MB/s    11143 MB/s
>
> Looks like those two might help:
>

That would mean only this is missing:
> 49200d17d27d x86/fpu/64: Don't FNINIT in kernel_fpu_begin()


as this one landed in 5.10.11:
> e45122893a98 x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize state
>

--
Thomas