From: Yi Sun <yi.sun@unisoc.com>
To: <yury.norov@gmail.com>, <mnazarewicz@gmail.com>
Cc: <akpm@linux-foundation.org>, <mina86@mina86.com>,
<akinobu.mita@gmail.com>, <linux-kernel@vger.kernel.org>,
<yi.sun@unisoc.com>
Subject: [PATCH v3 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off()
Date: Thu, 14 May 2026 17:06:07 +0800 [thread overview]
Message-ID: <20260514090607.231387-3-yi.sun@unisoc.com> (raw)
In-Reply-To: <20260514090607.231387-1-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..9b589643f72a 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_from(map, end, index);
if (i < end) {
start = i + 1;
goto again;
--
2.34.1
next prev parent reply other threads:[~2026-05-14 9:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-14 9:06 [PATCH v3 0/2] Improve the performance of bitmap_find_next_zero_area_off() Yi Sun
2026-05-14 9:06 ` [PATCH v3 1/2] lib: bitmap: add find_last_bit_from() and _find_last_bit_from() Yi Sun
2026-05-14 10:51 ` Michał Nazarewicz
2026-05-14 16:49 ` Yury Norov
2026-05-14 9:06 ` Yi Sun [this message]
2026-05-14 10:51 ` [PATCH v3 2/2] lib: bitmap: reduce the number of goto again in bitmap_find_next_zero_area_off() Michał Nazarewicz
2026-05-14 17:18 ` Yury Norov
2026-05-14 15:54 ` [PATCH v3 0/2] Improve the performance of bitmap_find_next_zero_area_off() Yury Norov
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