linux-kernel - Re: [PATCH] lib/find_bit: Add find_prev_*

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Message-ID: <20201202173701.GM4077@smile.fi.intel.com>
Date:   Wed, 2 Dec 2020 19:37:01 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Yun Levi <ppbuk5246@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>, dushistov@...l.ru,
        Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        William Breathitt Gray <vilhelm.gray@...il.com>,
        richard.weiyang@...ux.alibaba.com, joseph.qi@...ux.alibaba.com,
        skalluru@...vell.com, Josh Poimboeuf <jpoimboe@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH] lib/find_bit: Add find_prev_*_bit functions.

On Wed, Dec 02, 2020 at 09:26:05AM -0800, Yury Norov wrote:
> On Wed, Dec 2, 2020 at 3:50 AM Yun Levi <ppbuk5246@...il.com> wrote:

...

>  I think this patch has some good catches. We definitely need to implement
> find_last_zero_bit(), as it is used by fs/ufs, and their local
> implementation is not optimal.

Side note: speaking of performance, any plans to fix for_each_*_bit*() for
cases when the nbits is known to be <= BITS_PER_LONG?

Now it makes an awful code generation (something like few hundred bytes of
code).

-- 
With Best Regards,
Andy Shevchenko