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SubjectRe: [PATCH] arm64:crc:accelerated-crc32-by-64bytes
On Sun, 18 Nov 2018 at 23:30, Rui Sun <sunrui26@huawei.com> wrote:
>
> add 64 bytes loop to acceleration calculation
>

Can you share some performance numbers please?

Also, we don't need 64 byte, 32 byte and 16 byte code paths: just make
the 8 byte one a loop as well, and drop the 32 byte and 16 byte ones.


> Signed-off-by: Rui Sun <sunrui26@huawei.com>
> ---
> arch/arm64/lib/crc32.S | 54 ++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/lib/crc32.S b/arch/arm64/lib/crc32.S
> index 5bc1e85..2b37009 100644
> --- a/arch/arm64/lib/crc32.S
> +++ b/arch/arm64/lib/crc32.S
> @@ -15,15 +15,61 @@
> .cpu generic+crc
>
> .macro __crc32, c
> -0: subs x2, x2, #16
> - b.mi 8f
> +
> +64: cmp x2, #64
> + b.lt 32f
> +
> + adds x11, x1, #16
> + adds x12, x1, #32
> + adds x13, x1, #48
> +
> +0 : subs x2, x2, #64
> + b.mi 32f
> +
> + ldp x3, x4, [x1], #64
> + ldp x5, x6, [x11], #64
> + ldp x7, x8, [x12], #64
> + ldp x9, x10,[x13], #64
> +

Can we do this instead, and get rid of the temp variables?

ldp x3, x4, [x1], #64
ldp x5, x6, [x1, #-48]
ldp x7, x8, [x1, #-32]
ldp x9, x10,[x1, #-16]

> + CPU_BE( rev x3, x3 )
> + CPU_BE( rev x4, x4 )
> + CPU_BE( rev x5, x5 )
> + CPU_BE( rev x6, x6 )
> + CPU_BE( rev x7, x7 )
> + CPU_BE( rev x8, x8 )
> + CPU_BE( rev x9, x9 )
> + CPU_BE( rev x10,x10 )
> +
> + crc32\c\()x w0, w0, x3
> + crc32\c\()x w0, w0, x4
> + crc32\c\()x w0, w0, x5
> + crc32\c\()x w0, w0, x6
> + crc32\c\()x w0, w0, x7
> + crc32\c\()x w0, w0, x8
> + crc32\c\()x w0, w0, x9
> + crc32\c\()x w0, w0, x10
> +
> + b.ne 0b
> + ret
> +
> +32: tbz x2, #5, 16f
> + ldp x3, x4, [x1], #16
> + ldp x5, x6, [x1], #16
> +CPU_BE( rev x3, x3 )
> +CPU_BE( rev x4, x4 )
> +CPU_BE( rev x5, x5 )
> +CPU_BE( rev x6, x6 )
> + crc32\c\()x w0, w0, x3
> + crc32\c\()x w0, w0, x4
> + crc32\c\()x w0, w0, x5
> + crc32\c\()x w0, w0, x6
> +
> +16: tbz x2, #4, 8f
> ldp x3, x4, [x1], #16
> CPU_BE( rev x3, x3 )
> CPU_BE( rev x4, x4 )
> crc32\c\()x w0, w0, x3
> crc32\c\()x w0, w0, x4
> - b.ne 0b
> - ret
>
> 8: tbz x2, #3, 4f
> ldr x3, [x1], #8
> --
> 1.8.3.1
>

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