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From: Yury Norov <yury.norov@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	Russell King <linux+etnaviv@armlinux.org.uk>,
	Christian Gmeiner <christian.gmeiner@gmail.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Jean Delvare <jdelvare@suse.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Marc Zyngier <maz@kernel.org>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wei Yang <richard.weiyang@linux.alibaba.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Alexey Klimov <aklimov@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-hwmon@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>
Subject: [PATCH 2/3] find: micro-optimize for_each_{set,clear}_bit()
Date: Fri, 18 Jun 2021 12:57:34 -0700	[thread overview]
Message-ID: <20210618195735.55933-3-yury.norov@gmail.com> (raw)
In-Reply-To: <20210618195735.55933-1-yury.norov@gmail.com>

The macros iterate thru all set/clear bits in a bitmap. They search a
first bit using find_first_bit(), and the rest bits using find_next_bit().

Since find_next_bit() is called shortly after find_first_bit(), we can
save few lines of I-cache by not using find_first_bit().

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/find.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/find.h b/include/linux/find.h
index 4500e8ab93e2..ae9ed52b52b8 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -280,7 +280,7 @@ unsigned long find_next_bit_le(const void *addr, unsigned
 #endif
 
 #define for_each_set_bit(bit, addr, size) \
-	for ((bit) = find_first_bit((addr), (size));		\
+	for ((bit) = find_next_bit((addr), (size), 0);		\
 	     (bit) < (size);					\
 	     (bit) = find_next_bit((addr), (size), (bit) + 1))
 
@@ -291,7 +291,7 @@ unsigned long find_next_bit_le(const void *addr, unsigned
 	     (bit) = find_next_bit((addr), (size), (bit) + 1))
 
 #define for_each_clear_bit(bit, addr, size) \
-	for ((bit) = find_first_zero_bit((addr), (size));	\
+	for ((bit) = find_next_zero_bit((addr), (size), 0);	\
 	     (bit) < (size);					\
 	     (bit) = find_next_zero_bit((addr), (size), (bit) + 1))
 
-- 
2.30.2


  parent reply	other threads:[~2021-06-19  7:44 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 19:57 [PATCH 0/3] for_each_*_bit: move to find.h and reconsider Yury Norov
2021-06-18 19:57 ` [PATCH 1/3] include/linux: move for_each_bit() macros from bitops.h to find.h Yury Norov
2021-06-19 10:50   ` Andy Shevchenko
2021-06-18 19:57 ` Yury Norov [this message]
2021-06-19 10:50   ` [PATCH 2/3] find: micro-optimize for_each_{set,clear}_bit() Andy Shevchenko
2021-06-19 16:24   ` Marc Zyngier
2021-06-19 17:28     ` Yury Norov
2021-06-27 16:47       ` Yury Norov
2021-06-18 19:57 ` [PATCH 3/3] Replace for_each_*_bit_from() with for_each_*_bit() where appropriate Yury Norov
2021-06-19 10:49   ` Andy Shevchenko
2021-06-19 10:55     ` Andy Shevchenko
2021-06-21 20:17   ` Guenter Roeck
2021-06-21 21:34     ` Yury Norov
2021-07-28 14:57 ` [PATCH 0/3] for_each_*_bit: move to find.h and reconsider Yury Norov

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