Re: [PATCH 5/8] lib: add find_first_and_bit()

[Alexey Klimov]

On Sat, Jun 12, 2021 at 1:36 PM Yury Norov <yury.norov@xxxxxxxxx> wrote:
>
> Currently find_first_and_bit() is an alias to find_next_and_bit(). However,
> it is widely used in cpumask, so it worth to optimize it. This patch adds
> its own implementation for find_first_and_bit().
>
> On x86_64 find_bit_benchmark says:
>
> Before (#define find_first_and_bit(...) find_next_and_bit(..., 0):
> Start testing find_bit() with random-filled bitmap
> [  140.291468] find_first_and_bit:           46890919 ns,  32671 iterations
> Start testing find_bit() with sparse bitmap
> [  140.295028] find_first_and_bit:               7103 ns,      1 iterations
>
> After:
> Start testing find_bit() with random-filled bitmap
> [  162.574907] find_first_and_bit:           25045813 ns,  32846 iterations
> Start testing find_bit() with sparse bitmap
> [  162.578458] find_first_and_bit:               4900 ns,      1 iterations
>
> (Thanks to Alexey Klimov for thorough testing.)
>
> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>

Tested-by: Alexey Klimov <aklimov@xxxxxxxxxx>

[..]

Best regards,
Alexey