linux-kernel - Re: [PATCH 2/2] bitmap: introduce for_each_set

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Date:   Thu, 8 Jul 2021 23:21:05 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 2/2] bitmap: introduce for_each_set_bitrange

On Thu, Jul 08, 2021 at 08:45:19PM -0700, Yury Norov 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. We can do
> better by detecting ranges of set bits.
> 
> This patch introduces a macro for_each_set_bitrange and uses it in
> bitmap_list_string(). In my environment, before/after is 943008/31008 ns.

Ah, it seems we already have bitmap_for_each_{set,clear}_region() with
the same functionality. I'll check everything again and submit v2 soon.