From: "Michał Nazarewicz" <mina86@mina86.com>
To: Yi Sun <yi.sun@unisoc.com>,
yi.sun@unisoc.com, yury.norov@gmail.com,
akpm@linux-foundation.org
Cc: akinobu.mita@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off()
Date: Tue, 12 May 2026 13:32:36 +0200 [thread overview]
Message-ID: <d7jy92t8oqk3m3vfvi70gn68@mina86.com> (raw)
In-Reply-To: <20260512040659.2992142-3-yi.sun@unisoc.com>
On Tue, May 12 2026, Yi Sun wrote:
> Finding a contiguous free region in a highly fragmented
> bitmap is not easy and may require many repeated attempts.
> Therefore, find_next_bit(map, end, index) is not the optimal choice.
> This is because there may be multiple scattered free regions
> within the range [index, end) and none of them will meet the length
> requirement of @nr.
> Instead, it's sufficient to directly find the last bit within
> the range [index, end), thus reducing unnecessary "goto again" calls.
>
> Signed-off-by: Yi Sun <yi.sun@unisoc.com>
Acked-by: Michał Nazarewicz <mina86@mina86.com>
> ---
> lib/bitmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index b9bfa157e095..53961a7683a4 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -442,7 +442,7 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
> end = index + nr;
> if (end > size)
> return end;
> - i = find_next_bit(map, end, index);
> + i = find_last_bit_range(map, end, index);
> if (i < end) {
> start = i + 1;
> goto again;
--
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴィツ
«If at first you don’t succeed, give up skydiving»
next prev parent reply other threads:[~2026-05-12 11:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 4:06 [PATCH 0/2] Improve the performance of bitmap_find_next_zero_area_off() Yi Sun
2026-05-12 4:06 ` [PATCH 1/2] lib: bitmap: add find_last_bit_range() and _find_last_bit_range() Yi Sun
2026-05-12 11:31 ` Michał Nazarewicz
2026-05-12 16:46 ` Yury Norov
2026-05-12 4:06 ` [PATCH 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off() Yi Sun
2026-05-12 11:32 ` Michał Nazarewicz [this message]
2026-05-12 16:51 ` Yury Norov
2026-05-14 3:02 ` 答复: " 孙毅 (Yi Sun)
2026-05-12 16:34 ` [PATCH 0/2] Improve the performance of bitmap_find_next_zero_area_off() Yury Norov
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