linux-kernel - Re: [PATCH 7/8] lib: add fast path for find_next_*

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Message-ID: <YBgG35UTDLpVSYWV@smile.fi.intel.com>
Date:   Mon, 1 Feb 2021 15:49:19 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yury Norov <yury.norov@...il.com>
Cc:     linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
        linux-sh@...r.kernel.org, linux-arch@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, Arnd Bergmann <arnd@...db.de>,
        Dennis Zhou <dennis@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        David Sterba <dsterba@...e.com>,
        Stefano Brivio <sbrivio@...hat.com>,
        "Ma, Jianpeng" <jianpeng.ma@...el.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Joe Perches <joe@...ches.com>
Subject: Re: [PATCH 7/8] lib: add fast path for find_next_*_bit()

On Sat, Jan 30, 2021 at 11:17:18AM -0800, Yury Norov wrote:
> Similarly to bitmap functions, find_next_*_bit() users will benefit
> if we'll handle a case of bitmaps that fit into a single word. In the
> very best case, the compiler may replace a function call with a
> single ffs or ffz instruction.

Would be nice to have the examples how it reduces the actual code size (based
on the existing code in kernel, especially in widely used frameworks /
subsystems, like PCI).

-- 
With Best Regards,
Andy Shevchenko