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Message-Id: <20190821074200.2203-1-efremov@ispras.ru>
Date: Wed, 21 Aug 2019 10:42:00 +0300
From: Denis Efremov <efremov@...ras.ru>
To: akpm@...ux-foundation.org
Cc: Denis Efremov <efremov@...ras.ru>,
Akinobu Mita <akinobu.mita@...il.com>, Jan Kara <jack@...e.cz>,
Matthew Wilcox <matthew@....cx>, linux-kernel@...r.kernel.org,
dm-devel@...hat.com, linux-fsdevel@...r.kernel.org,
linux-media@...r.kernel.org, Erdem Tumurov <erdemus@...il.com>,
Vladimir Shelekhov <vshel@....nsk.su>
Subject: [PATCH] lib/memweight.c: optimize by inlining bitmap_weight()
This patch inlines bitmap_weight() call. Thus, removing the BUG_ON,
and 'longs to bits -> bits to longs' conversion by directly calling
hweight_long().
./scripts/bloat-o-meter lib/memweight.o.old lib/memweight.o.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10)
Function old new delta
memweight 162 152 -10
Co-developed-by: Erdem Tumurov <erdemus@...il.com>
Co-developed-by: Vladimir Shelekhov <vshel@....nsk.su>
Signed-off-by: Erdem Tumurov <erdemus@...il.com>
Signed-off-by: Vladimir Shelekhov <vshel@....nsk.su>
Signed-off-by: Denis Efremov <efremov@...ras.ru>
---
lib/memweight.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/lib/memweight.c b/lib/memweight.c
index 94dd72ccaa7f..f050b2b4c5e2 100644
--- a/lib/memweight.c
+++ b/lib/memweight.c
@@ -20,11 +20,13 @@ size_t memweight(const void *ptr, size_t bytes)
longs = bytes / sizeof(long);
if (longs) {
- BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
- ret += bitmap_weight((unsigned long *)bitmap,
- longs * BITS_PER_LONG);
+ const unsigned long *bitmap_long =
+ (const unsigned long *)bitmap;
+
bytes -= longs * sizeof(long);
- bitmap += longs * sizeof(long);
+ for (; longs > 0; longs--, bitmap_long++)
+ ret += hweight_long(*bitmap_long);
+ bitmap = (const unsigned char *)bitmap_long;
}
/*
* The reason that this last loop is distinct from the preceding
--
2.21.0
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