From: Denis Efremov <efremov@ispras.ru>
To: akpm@linux-foundation.org
Cc: Denis Efremov <efremov@ispras.ru>,
Akinobu Mita <akinobu.mita@gmail.com>, Jan Kara <jack@suse.cz>,
Matthew Wilcox <matthew@wil.cx>,
linux-kernel@vger.kernel.org, dm-devel@redhat.com,
linux-fsdevel@vger.kernel.org, linux-media@vger.kernel.org,
Erdem Tumurov <erdemus@gmail.com>,
Vladimir Shelekhov <vshel@iis.nsk.su>
Subject: [PATCH] lib/memweight.c: optimize by inlining bitmap_weight()
Date: Wed, 21 Aug 2019 10:42:00 +0300 [thread overview]
Message-ID: <20190821074200.2203-1-efremov@ispras.ru> (raw)
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@gmail.com>
Co-developed-by: Vladimir Shelekhov <vshel@iis.nsk.su>
Signed-off-by: Erdem Tumurov <erdemus@gmail.com>
Signed-off-by: Vladimir Shelekhov <vshel@iis.nsk.su>
Signed-off-by: Denis Efremov <efremov@ispras.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
next reply other threads:[~2019-08-21 7:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 7:42 Denis Efremov [this message]
2019-08-22 1:25 ` [PATCH] lib/memweight.c: optimize by inlining bitmap_weight() Andrew Morton
2019-08-22 7:30 ` Denis Efremov
2019-08-24 10:01 ` [PATCH v2] lib/memweight.c: open codes bitmap_weight() Denis Efremov
2019-08-25 6:11 ` Matthew Wilcox
2019-08-25 11:39 ` Denis Efremov
2019-08-26 18:39 ` Matthew Wilcox
2019-09-13 11:48 ` Denis Efremov
2019-09-13 13:41 ` efremov
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