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From: Yi Sun <yi.sun@unisoc.com>
To: <yi.sun@unisoc.com>, <yury.norov@gmail.com>, <akpm@linux-foundation.org>
Cc: <mina86@mina86.com>, <akinobu.mita@gmail.com>,
	<linux-kernel@vger.kernel.org>
Subject: [PATCH 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off()
Date: Tue, 12 May 2026 12:06:59 +0800	[thread overview]
Message-ID: <20260512040659.2992142-3-yi.sun@unisoc.com> (raw)
In-Reply-To: <20260512040659.2992142-1-yi.sun@unisoc.com>

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>
---
 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;
-- 
2.34.1


  parent reply	other threads:[~2026-05-12  4:09 UTC|newest]

Thread overview: 8+ 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 ` Yi Sun [this message]
2026-05-12 11:32   ` [PATCH 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off() Michał Nazarewicz
2026-05-12 16:51   ` Yury Norov
2026-05-12 16:34 ` [PATCH 0/2] Improve the performance of bitmap_find_next_zero_area_off() Yury Norov

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