From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id E9C2F6B0266 for ; Mon, 26 Dec 2016 23:13:41 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id 127so205637468pfg.5 for ; Mon, 26 Dec 2016 20:13:41 -0800 (PST) Received: from mailout3.samsung.com (mailout3.samsung.com. [203.254.224.33]) by mx.google.com with ESMTPS id n77si13168726pfj.225.2016.12.26.20.13.40 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 26 Dec 2016 20:13:40 -0800 (PST) MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Received: from epcas1p3.samsung.com (unknown [182.195.41.47]) by mailout3.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0OIT013IVT2RHL70@mailout3.samsung.com> for linux-mm@kvack.org; Tue, 27 Dec 2016 13:13:39 +0900 (KST) Content-transfer-encoding: 8BIT Subject: Re: [PATCH] lib: bitmap: introduce bitmap_find_next_zero_area_and_size From: Jaewon Kim Message-id: <5861EA98.50606@samsung.com> Date: Tue, 27 Dec 2016 13:14:16 +0900 In-reply-to: References: <1482725891-10866-1-git-send-email-jaewon31.kim@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz , gregkh@linuxfoundation.org, akpm@linux-foundation.org Cc: labbott@redhat.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 On 2016e?? 12i?? 27i? 1/4 06:09, Michal Nazarewicz wrote: > On Mon, Dec 26 2016, Jaewon Kim wrote: >> There was no bitmap API which returns both next zero index and size of zeros >> from that index. > Is it really needed? Does it noticeably simplifies callers? Why cana??t > caller get the size by themselves if they need it? Hi thank you for your comment. As some other functions, this is a helper function to use easily. Without this patch, we can get the size by using two bitmap functions. >> 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); >> >> 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