Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753767AbcL0KFt (ORCPT ); Tue, 27 Dec 2016 05:05:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:54886 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753144AbcL0KFk (ORCPT ); Tue, 27 Dec 2016 05:05:40 -0500 Date: Tue, 27 Dec 2016 11:05:35 +0100 From: Michal Hocko To: Jaewon Kim Cc: gregkh@linuxfoundation.org, akpm@linux-foundation.org, labbott@redhat.com, mina86@mina86.com, m.szyprowski@samsung.com, gregory.0xf0@gmail.com, laurent.pinchart@ideasonboard.com, akinobu.mita@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com Subject: Re: [PATCH] lib: bitmap: introduce bitmap_find_next_zero_area_and_size Message-ID: <20161227100535.GB7662@dhcp22.suse.cz> References: <1482725891-10866-1-git-send-email-jaewon31.kim@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1482725891-10866-1-git-send-email-jaewon31.kim@samsung.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3914 Lines: 116 On Mon 26-12-16 13:18:11, Jaewon Kim 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); Who is going to use this function? I do not see any caller introduced by this patch. > Signed-off-by: Jaewon Kim > --- > include/linux/bitmap.h | 6 ++++++ > lib/bitmap.c | 25 +++++++++++++++++++++++++ > 2 files changed, 31 insertions(+) > > diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h > index 3b77588..b724a6c 100644 > --- a/include/linux/bitmap.h > +++ b/include/linux/bitmap.h > @@ -46,6 +46,7 @@ > * bitmap_clear(dst, pos, nbits) Clear specified bit area > * bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area > * bitmap_find_next_zero_area_off(buf, len, pos, n, mask) as above > + * bitmap_find_next_zero_area_and_size(buf, len, pos, n, mask) Find bit free area and its size > * bitmap_shift_right(dst, src, n, nbits) *dst = *src >> n > * bitmap_shift_left(dst, src, n, nbits) *dst = *src << n > * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src) > @@ -123,6 +124,11 @@ extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map, > unsigned long align_mask, > unsigned long align_offset); > > +extern unsigned long bitmap_find_next_zero_area_and_size(unsigned long *map, > + unsigned long size, > + unsigned long start, > + unsigned int *nr); > + > /** > * bitmap_find_next_zero_area - find a contiguous aligned zero area > * @map: The address to base the search on > diff --git a/lib/bitmap.c b/lib/bitmap.c > index 0b66f0e..d02817c 100644 > --- a/lib/bitmap.c > +++ b/lib/bitmap.c > @@ -332,6 +332,31 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map, > } > EXPORT_SYMBOL(bitmap_find_next_zero_area_off); > > +/** > + * bitmap_find_next_zero_area_and_size - find a contiguous aligned zero area > + * @map: The address to base the search on > + * @size: The bitmap size in bits > + * @start: The bitnumber to start searching at > + * @nr: The number of zeroed bits we've found > + */ > +unsigned long bitmap_find_next_zero_area_and_size(unsigned long *map, > + unsigned long size, > + unsigned long start, > + unsigned int *nr) > +{ > + unsigned long index, i; > + > + *nr = 0; > + index = find_next_zero_bit(map, size, start); > + > + if (index >= size) > + return index; > + i = find_next_bit(map, size, index); > + *nr = i - index; > + return index; > +} > +EXPORT_SYMBOL(bitmap_find_next_zero_area_and_size); > + > /* > * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers, > * second version by Paul Jackson, third by Joe Korty. > -- > 1.9.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Michal Hocko SUSE Labs