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

[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:

49200d17d27d x86/fpu/64: Don't FNINIT in kernel_fpu_begin()
e45122893a98 x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize state

-- 
Regards/Gruss,
    Boris.

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