linux-kernel - Re: [PATCH 17/17] vsprintf: rework bitmap_list

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Date:   Sun, 15 Aug 2021 14:09:45 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
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Subject: Re: [PATCH 17/17] vsprintf: rework bitmap_list_string

On Sun, Aug 15, 2021 at 12:21 AM Yury Norov <yury.norov@...il.com> wrote:
>
> bitmap_list_string() is very ineffective when printing bitmaps with long
> ranges of set bits because it calls find_next_bit for each bit in the
> bitmap.  We can do better by detecting ranges of set bits.
>
> In my environment, before/after is 943008/31008 ns.

I would add a couple of words, maybe in parentheses, to describe what
your environment is.

...

> +               buf = number(++buf, end, rtop - 1, default_dec_spec);

++buf is a bit confusing here. Since you will rewrite the buf value
anyway, I would write the parameter as buf + 1.

-- 
With Best Regards,
Andy Shevchenko