From: Yury Norov <yury.norov@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>,
linux-m68k@lists.linux-m68k.org, linux-arch@vger.kernel.org,
linux-sh@vger.kernel.org, Alexey Klimov <aklimov@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Arnd Bergmann <arnd@arndb.de>, David Sterba <dsterba@suse.com>,
Dennis Zhou <dennis@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Jianpeng Ma <jianpeng.ma@intel.com>,
Joe Perches <joe@perches.com>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Rich Felker <dalias@libc.org>,
Stefano Brivio <sbrivio@redhat.com>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>
Subject: [PATCH 08/14] lib/Kconfig: introduce FAST_PATH option
Date: Wed, 17 Feb 2021 20:05:06 -0800 [thread overview]
Message-ID: <20210218040512.709186-9-yury.norov@gmail.com> (raw)
In-Reply-To: <20210218040512.709186-1-yury.norov@gmail.com>
This series introduces fast paths for find_bit() routines. It is
beneficial for typical systems, but those who limited in I-cache
may be concerned about increasing the .text size of the Image.
To address this concern, one can disable FAST_PATH option in the config
and some save memory.
The effect of this option on my arm64 next-20210217 build is:
Before:
Sections:
Idx Name Size VMA LMA File off Algn
0 .head.text 00010000 ffff800010000000 ffff800010000000 00010000 2**16
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .text 0115e3a8 ffff800010010000 ffff800010010000 00020000 2**16
CONTENTS, ALLOC, LOAD, READONLY, CODE
2 .got.plt 00000018 ffff80001116e3a8 ffff80001116e3a8 0117e3a8 2**3
CONTENTS, ALLOC, LOAD, DATA
3 .rodata 007a72ca ffff800011170000 ffff800011170000 01180000 2**12
CONTENTS, ALLOC, LOAD, DATA
...
After:
Sections:
Idx Name Size VMA LMA File off Algn
0 .head.text 00010000 ffff800010000000 ffff800010000000 00010000 2**16
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .text 011623a8 ffff800010010000 ffff800010010000 00020000 2**16
CONTENTS, ALLOC, LOAD, READONLY, CODE
2 .got.plt 00000018 ffff8000111723a8 ffff8000111723a8 011823a8 2**3
CONTENTS, ALLOC, LOAD, DATA
3 .rodata 007a772a ffff800011180000 ffff800011180000 01190000 2**12
CONTENTS, ALLOC, LOAD, DATA
...
Notice that this is the cumulive effect on already existing fast paths
controlled by SMALL_CONST() together with ones added by this series.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
include/asm-generic/bitsperlong.h | 4 ++++
lib/Kconfig | 7 +++++++
2 files changed, 11 insertions(+)
diff --git a/include/asm-generic/bitsperlong.h b/include/asm-generic/bitsperlong.h
index 0eeb77544f1d..209e531074c1 100644
--- a/include/asm-generic/bitsperlong.h
+++ b/include/asm-generic/bitsperlong.h
@@ -23,6 +23,10 @@
#define BITS_PER_LONG_LONG 64
#endif
+#ifdef CONFIG_FAST_PATH
#define SMALL_CONST(n) (__builtin_constant_p(n) && (unsigned long)(n) < BITS_PER_LONG)
+#else
+#define SMALL_CONST(n) (0)
+#endif
#endif /* __ASM_GENERIC_BITS_PER_LONG */
diff --git a/lib/Kconfig b/lib/Kconfig
index a38cc61256f1..7a1b9c8d2a32 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -39,6 +39,13 @@ config PACKING
When in doubt, say N.
+config FAST_PATH
+ bool "Enable fast path code generation"
+ default y
+ help
+ This option enables fast path optimization with the cost of increasing
+ the text section.
+
config BITREVERSE
tristate
--
2.25.1
next prev parent reply other threads:[~2021-02-18 4:08 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-18 4:04 [PATCH v3 00/14] lib/find_bit: fast path for small bitmaps Yury Norov
2021-02-18 4:04 ` [PATCH 01/14] tools: disable -Wno-type-limits Yury Norov
2021-02-18 4:05 ` [PATCH 02/14] tools: bitmap: sync function declarations with the kernel Yury Norov
2021-02-18 4:05 ` [PATCH 03/14] arch: rearrange headers inclusion order in asm/bitops for m68k and sh Yury Norov
2021-02-18 4:05 ` [PATCH 04/14] lib: introduce BITS_{FIRST,LAST} macro Yury Norov
2021-02-18 22:51 ` Rasmus Villemoes
2021-03-12 4:30 ` Yury Norov
2021-02-18 4:05 ` [PATCH 05/14] tools: sync BITS_MASK macros with the kernel Yury Norov
2021-02-18 4:05 ` [PATCH 06/14] bitsperlong.h: introduce SMALL_CONST() macro Yury Norov
2021-02-18 23:07 ` Rasmus Villemoes
2021-03-12 5:28 ` Yury Norov
2021-03-12 9:12 ` Rasmus Villemoes
2021-03-12 21:53 ` Yury Norov
2021-02-18 4:05 ` [PATCH 07/14] tools: " Yury Norov
2021-02-18 4:05 ` Yury Norov [this message]
2021-02-18 15:15 ` [PATCH 08/14] lib/Kconfig: introduce FAST_PATH option Andy Shevchenko
2021-02-18 19:24 ` Yury Norov
2021-02-19 10:52 ` Andy Shevchenko
2021-02-18 4:05 ` [PATCH 09/14] lib: inline _find_next_bit() wrappers Yury Norov
2021-02-18 4:05 ` [PATCH 10/14] tools: sync find_next_bit implementation Yury Norov
2021-02-18 4:05 ` [PATCH 11/14] lib: add fast path for find_next_*_bit() Yury Norov
2021-02-18 15:24 ` Andy Shevchenko
2021-02-18 4:05 ` [PATCH 12/14] lib: add fast path for find_first_*_bit() and find_last_bit() Yury Norov
2021-02-18 4:05 ` [PATCH 13/14] tools: sync lib/find_bit implementation Yury Norov
2021-02-18 4:05 ` [PATCH 14/14] MAINTAINERS: Add entry for the bitmap API Yury Norov
2021-02-18 15:28 ` Andy Shevchenko
2021-02-18 15:34 ` Yury Norov
2021-03-12 9:15 ` Rasmus Villemoes
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