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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Mon, 16 Jan 2017 19:59:50 +0200
Message-ID: <CAHp75VfO6POaH+AsoS9kU1y+CEKwuJ0FNSB8Bg866X3iXS9DRA@mail.gmail.com>
Subject: Re: [PATCH] lib: bitmap: introduce bitmap_find_next_zero_area_and_size
To: Jaewon Kim <jaewon31.kim@samsung.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>, labbott@redhat.com,
        Michal Nazarewicz <mina86@mina86.com>, m.szyprowski@samsung.com,
        gregory.0xf0@gmail.com,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        akinobu.mita@gmail.com, linux-mm@kvack.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        jaewon31.kim@gmail.com
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On Mon, Dec 26, 2016 at 6:18 AM, Jaewon Kim <jaewon31.kim@samsung.com> wrote:
> There was no bitmap API which returns both next zero index and size of zeros
> from that index.
>
> This is helpful to look fragmentation. This is an test code to look size of zeros.
> Test result is '10+9+994=>1013 found of total: 1024'
>
> unsigned long search_idx, found_idx, nr_found_tot;
> unsigned long bitmap_max;
> unsigned int nr_found;
> unsigned long *bitmap;
>
> search_idx = nr_found_tot = 0;
> bitmap_max = 1024;
> bitmap = kzalloc(BITS_TO_LONGS(bitmap_max) * sizeof(long),
>                  GFP_KERNEL);
>
> /* test bitmap_set offset, count */
> bitmap_set(bitmap, 10, 1);
> bitmap_set(bitmap, 20, 10);
>
> for (;;) {
>         found_idx = bitmap_find_next_zero_area_and_size(bitmap,
>                                 bitmap_max, search_idx, &nr_found);
>         if (found_idx >= bitmap_max)
>                 break;
>         if (nr_found_tot == 0)
>                 printk("%u", nr_found);
>         else
>                 printk("+%u", nr_found);
>         nr_found_tot += nr_found;
>         search_idx = found_idx + nr_found;
> }
> printk("=>%lu found of total: %lu\n", nr_found_tot, bitmap_max);

Tests should be added to corresponding test module. See lib/*test*
files for details.

-- 
With Best Regards,
Andy Shevchenko