From: Andrew Morton <akpm@linux-foundation.org>
To: aklimov@redhat.com, akpm@linux-foundation.org,
andy.shevchenko@gmail.com, arnd@arndb.de, dalias@libc.org,
dennis@kernel.org, dsterba@suse.com, geert@linux-m68k.org,
glaubitz@physik.fu-berlin.de, jianpeng.ma@intel.com,
joe@perches.com, jpoimboe@redhat.com, linux-mm@kvack.org,
linux@rasmusvillemoes.dk, mm-commits@vger.kernel.org,
richard.weiyang@linux.alibaba.com, sbrivio@redhat.com,
torvalds@linux-foundation.org, wsa+renesas@sang-engineering.com,
ysato@users.osdn.me, yury.norov@gmail.com
Subject: [patch 23/91] lib: add fast path for find_first_*_bit() and find_last_bit()
Date: Thu, 06 May 2021 18:03:14 -0700 [thread overview]
Message-ID: <20210507010314.JeRDJQNxO%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210506180126.03e1baee7ca52bedb6cc6003@linux-foundation.org>
From: Yury Norov <yury.norov@gmail.com>
Subject: lib: add fast path for find_first_*_bit() and find_last_bit()
Similarly to bitmap functions, users would benefit if we'll handle a case
of small-size bitmaps that fit into a single word.
While here, move the find_last_bit() declaration to bitops/find.h where
other find_*_bit() functions sit.
Link: https://lkml.kernel.org/r/20210401003153.97325-11-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Alexey Klimov <aklimov@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jianpeng Ma <jianpeng.ma@intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Stefano Brivio <sbrivio@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/asm-generic/bitops/find.h | 50 +++++++++++++++++++++++++---
include/linux/bitops.h | 12 ------
lib/find_bit.c | 12 +++---
3 files changed, 52 insertions(+), 22 deletions(-)
--- a/include/asm-generic/bitops/find.h~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/include/asm-generic/bitops/find.h
@@ -5,6 +5,9 @@
extern unsigned long _find_next_bit(const unsigned long *addr1,
const unsigned long *addr2, unsigned long nbits,
unsigned long start, unsigned long invert, unsigned long le);
+extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size);
#ifndef find_next_bit
/**
@@ -102,8 +105,17 @@ unsigned long find_next_zero_bit(const u
* Returns the bit number of the first set bit.
* If no bits are set, returns @size.
*/
-extern unsigned long find_first_bit(const unsigned long *addr,
- unsigned long size);
+static inline
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr & GENMASK(size - 1, 0);
+
+ return val ? __ffs(val) : size;
+ }
+
+ return _find_first_bit(addr, size);
+}
/**
* find_first_zero_bit - find the first cleared bit in a memory region
@@ -113,8 +125,17 @@ extern unsigned long find_first_bit(cons
* Returns the bit number of the first cleared bit.
* If no bits are zero, returns @size.
*/
-extern unsigned long find_first_zero_bit(const unsigned long *addr,
- unsigned long size);
+static inline
+unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr | ~GENMASK(size - 1, 0);
+
+ return val == ~0UL ? size : ffz(val);
+ }
+
+ return _find_first_zero_bit(addr, size);
+}
#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifndef find_first_bit
@@ -126,6 +147,27 @@ extern unsigned long find_first_zero_bit
#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
+#ifndef find_last_bit
+/**
+ * find_last_bit - find the last set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The number of bits to search
+ *
+ * Returns the bit number of the last set bit, or size.
+ */
+static inline
+unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val = *addr & GENMASK(size - 1, 0);
+
+ return val ? __fls(val) : size;
+ }
+
+ return _find_last_bit(addr, size);
+}
+#endif
+
/**
* find_next_clump8 - find next 8-bit clump with set bits in a memory region
* @clump: location to store copy of found clump
--- a/include/linux/bitops.h~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/include/linux/bitops.h
@@ -286,17 +286,5 @@ static __always_inline void __assign_bit
})
#endif
-#ifndef find_last_bit
-/**
- * find_last_bit - find the last set bit in a memory region
- * @addr: The address to start the search at
- * @size: The number of bits to search
- *
- * Returns the bit number of the last set bit, or size.
- */
-extern unsigned long find_last_bit(const unsigned long *addr,
- unsigned long size);
-#endif
-
#endif /* __KERNEL__ */
#endif
--- a/lib/find_bit.c~lib-add-fast-path-for-find_first__bit-and-find_last_bit
+++ a/lib/find_bit.c
@@ -75,7 +75,7 @@ EXPORT_SYMBOL(_find_next_bit);
/*
* Find the first set bit in a memory region.
*/
-unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
{
unsigned long idx;
@@ -86,14 +86,14 @@ unsigned long find_first_bit(const unsig
return size;
}
-EXPORT_SYMBOL(find_first_bit);
+EXPORT_SYMBOL(_find_first_bit);
#endif
#ifndef find_first_zero_bit
/*
* Find the first cleared bit in a memory region.
*/
-unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
{
unsigned long idx;
@@ -104,11 +104,11 @@ unsigned long find_first_zero_bit(const
return size;
}
-EXPORT_SYMBOL(find_first_zero_bit);
+EXPORT_SYMBOL(_find_first_zero_bit);
#endif
#ifndef find_last_bit
-unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
{
if (size) {
unsigned long val = BITMAP_LAST_WORD_MASK(size);
@@ -124,7 +124,7 @@ unsigned long find_last_bit(const unsign
}
return size;
}
-EXPORT_SYMBOL(find_last_bit);
+EXPORT_SYMBOL(_find_last_bit);
#endif
unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
_
next prev parent reply other threads:[~2021-05-07 1:03 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 1:01 incoming Andrew Morton
2021-05-07 1:02 ` [patch 01/91] alpha: eliminate old-style function definitions Andrew Morton
2021-05-07 1:02 ` [patch 02/91] alpha: csum_partial_copy.c: add function prototypes from <net/checksum.h> Andrew Morton
2021-05-07 1:02 ` [patch 03/91] fs/proc/generic.c: fix incorrect pde_is_permanent check Andrew Morton
2021-05-07 1:02 ` [patch 04/91] proc: save LOC in __xlate_proc_name() Andrew Morton
2021-05-07 2:24 ` Linus Torvalds
2021-05-07 1:02 ` [patch 05/91] proc: mandate ->proc_lseek in "struct proc_ops" Andrew Morton
2021-05-07 1:02 ` [patch 06/91] proc: delete redundant subset=pid check Andrew Morton
2021-05-07 1:02 ` [patch 07/91] selftests: proc: test subset=pid Andrew Morton
2021-05-07 1:02 ` [patch 08/91] proc/sysctl: fix function name error in comments Andrew Morton
2021-05-07 1:02 ` [patch 09/91] include: remove pagemap.h from blkdev.h Andrew Morton
2021-05-07 1:02 ` [patch 10/91] kernel.h: drop inclusion in bitmap.h Andrew Morton
2021-05-07 1:02 ` [patch 11/91] linux/profile.h: remove unnecessary declaration Andrew Morton
2021-05-07 1:02 ` [patch 12/91] kernel/async.c: fix pr_debug statement Andrew Morton
2021-05-07 1:02 ` [patch 13/91] kernel/cred.c: make init_groups static Andrew Morton
2021-05-07 1:02 ` [patch 14/91] tools: disable -Wno-type-limits Andrew Morton
2021-05-07 1:02 ` [patch 15/91] tools: bitmap: sync function declarations with the kernel Andrew Morton
2021-05-07 1:02 ` [patch 16/91] tools: sync BITMAP_LAST_WORD_MASK() macro " Andrew Morton
2021-05-07 1:02 ` [patch 17/91] arch: rearrange headers inclusion order in asm/bitops for m68k, sh and h8300 Andrew Morton
2021-05-07 1:02 ` [patch 18/91] lib: extend the scope of small_const_nbits() macro Andrew Morton
2021-05-07 1:03 ` [patch 19/91] tools: sync small_const_nbits() macro with the kernel Andrew Morton
2021-05-07 1:03 ` [patch 20/91] lib: inline _find_next_bit() wrappers Andrew Morton
2021-05-07 1:03 ` [patch 21/91] tools: sync find_next_bit implementation Andrew Morton
2021-05-07 1:03 ` [patch 22/91] lib: add fast path for find_next_*_bit() Andrew Morton
2021-05-07 1:03 ` Andrew Morton [this message]
2021-05-07 1:03 ` [patch 24/91] tools: sync lib/find_bit implementation Andrew Morton
2021-05-07 1:03 ` [patch 25/91] MAINTAINERS: add entry for the bitmap API Andrew Morton
2021-05-07 1:03 ` [patch 26/91] lib/bch.c: fix a typo in the file bch.c Andrew Morton
2021-05-07 1:03 ` [patch 27/91] lib: fix inconsistent indenting in process_bit1() Andrew Morton
2021-05-07 1:03 ` [patch 28/91] lib/list_sort.c: fix typo in function description Andrew Morton
2021-05-07 1:03 ` [patch 29/91] lib/genalloc.c: fix a typo Andrew Morton
2021-05-07 1:03 ` [patch 30/91] lib: crc8: pointer to data block should be const Andrew Morton
2021-05-07 1:03 ` [patch 31/91] lib: stackdepot: turn depot_lock spinlock to raw_spinlock Andrew Morton
2021-05-07 1:03 ` [patch 32/91] lib/percpu_counter: tame kernel-doc compile warning Andrew Morton
2021-05-07 1:03 ` [patch 33/91] lib/genalloc: add parameter description to fix doc " Andrew Morton
2021-05-07 1:03 ` [patch 34/91] lib: parser: clean up kernel-doc Andrew Morton
2021-05-07 1:03 ` [patch 35/91] include/linux/compat.h: remove unneeded declaration from COMPAT_SYSCALL_DEFINEx() Andrew Morton
2021-05-07 1:03 ` [patch 36/91] checkpatch: warn when missing newline in return sysfs_emit() formats Andrew Morton
2021-05-07 1:03 ` [patch 37/91] checkpatch: exclude four preprocessor sub-expressions from MACRO_ARG_REUSE Andrew Morton
2021-05-07 1:04 ` [patch 38/91] checkpatch: improve ALLOC_ARRAY_ARGS test Andrew Morton
2021-05-07 1:04 ` [patch 39/91] kselftest: introduce new epoll test case Andrew Morton
2021-05-07 1:04 ` [patch 40/91] fs/epoll: restore waking from ep_done_scan() Andrew Morton
2021-05-07 1:04 ` [patch 41/91] isofs: fix fall-through warnings for Clang Andrew Morton
2021-05-07 1:04 ` [patch 42/91] fs/nilfs2: fix misspellings using codespell tool Andrew Morton
2021-05-07 1:04 ` [patch 43/91] nilfs2: fix typos in comments Andrew Morton
2021-05-07 1:04 ` [patch 44/91] hpfs: replace one-element array with flexible-array member Andrew Morton
2021-05-07 1:04 ` [patch 45/91] do_wait: make PIDTYPE_PID case O(1) instead of O(n) Andrew Morton
2021-05-07 1:04 ` [patch 46/91] kernel/fork.c: simplify copy_mm() Andrew Morton
2021-05-07 1:04 ` [patch 47/91] kernel/fork.c: fix typos Andrew Morton
2021-05-07 1:04 ` [patch 48/91] kernel/crash_core: add crashkernel=auto for vmcore creation Andrew Morton
2021-05-07 7:25 ` Linus Torvalds
2021-05-08 3:13 ` Baoquan He
2021-05-08 3:29 ` Baoquan He
2021-05-07 8:16 ` David Hildenbrand
2021-05-08 8:51 ` Baoquan He
2021-05-08 9:22 ` David Hildenbrand
2021-05-10 4:53 ` Baoquan He
2021-05-10 8:32 ` David Hildenbrand
2021-05-10 10:43 ` Baoquan He
2021-05-10 11:01 ` David Hildenbrand
2021-05-10 11:44 ` Dave Young
2021-05-10 11:56 ` David Hildenbrand
2021-05-11 13:36 ` Baoquan He
2021-05-11 16:31 ` Mike Rapoport
2021-05-11 17:07 ` David Hildenbrand
2021-05-12 14:51 ` Baoquan He
2021-05-12 15:07 ` David Hildenbrand
2021-05-13 5:04 ` Baoquan He
2021-05-12 19:03 ` Kairui Song
2021-05-17 8:22 ` David Hildenbrand
2021-05-18 8:49 ` Baoquan He
2021-05-18 8:51 ` David Hildenbrand
2021-05-18 9:24 ` Dave Young
2021-05-12 14:13 ` Baoquan He
2021-05-12 7:42 ` Dave Young
2021-05-07 1:04 ` [patch 49/91] kexec: add kexec reboot string Andrew Morton
2021-05-07 1:04 ` [patch 50/91] kernel: kexec_file: fix error return code of kexec_calculate_store_digests() Andrew Morton
2021-05-07 1:04 ` [patch 51/91] kexec: dump kmessage before machine_kexec Andrew Morton
2021-05-07 1:04 ` [patch 52/91] gcov: combine common code Andrew Morton
2021-05-07 1:04 ` [patch 53/91] gcov: simplify buffer allocation Andrew Morton
2021-05-07 1:04 ` [patch 54/91] gcov: use kvmalloc() Andrew Morton
2021-05-07 1:04 ` [patch 55/91] gcov: clang: drop support for clang-10 and older Andrew Morton
2021-05-07 1:04 ` [patch 56/91] smp: kernel/panic.c - silence warnings Andrew Morton
2021-05-07 1:05 ` [patch 57/91] delayacct: clear right task's flag after blkio completes Andrew Morton
2021-05-07 1:05 ` [patch 58/91] gdb: lx-symbols: store the abspath() Andrew Morton
2021-05-07 1:05 ` [patch 59/91] scripts/gdb: document lx_current is only supported by x86 Andrew Morton
2021-05-07 1:05 ` [patch 60/91] scripts/gdb: add lx_current support for arm64 Andrew Morton
2021-05-07 1:05 ` [patch 61/91] kernel/resource: make walk_system_ram_res() find all busy IORESOURCE_SYSTEM_RAM resources Andrew Morton
2021-05-07 1:05 ` [patch 62/91] kernel/resource: make walk_mem_res() find all busy IORESOURCE_MEM resources Andrew Morton
2021-05-07 1:05 ` [patch 63/91] kernel/resource: remove first_lvl / siblings_only logic Andrew Morton
2021-05-07 1:05 ` [patch 64/91] kernel/resource: allow region_intersects users to hold resource_lock Andrew Morton
2021-05-07 1:05 ` [patch 65/91] kernel/resource: refactor __request_region to allow external locking Andrew Morton
2021-05-07 1:05 ` [patch 66/91] kernel/resource: fix locking in request_free_mem_region Andrew Morton
2021-05-07 1:05 ` [patch 67/91] selftests: remove duplicate include Andrew Morton
2021-05-07 1:05 ` [patch 68/91] kernel/async.c: stop guarding pr_debug() statements Andrew Morton
2021-05-07 1:05 ` [patch 69/91] kernel/async.c: remove async_unregister_domain() Andrew Morton
2021-05-07 1:05 ` [patch 70/91] init/initramfs.c: do unpacking asynchronously Andrew Morton
2021-05-07 1:05 ` [patch 71/91] modules: add CONFIG_MODPROBE_PATH Andrew Morton
2021-05-07 1:05 ` [patch 72/91] ipc/sem.c: mundane typo fixes Andrew Morton
2021-05-07 1:05 ` [patch 73/91] mm: fix some typos and code style problems Andrew Morton
2021-05-07 1:05 ` [patch 74/91] drivers/char: remove /dev/kmem for good Andrew Morton
2021-05-07 1:06 ` [patch 75/91] mm: remove xlate_dev_kmem_ptr() Andrew Morton
2021-05-07 1:06 ` [patch 76/91] mm/vmalloc: remove vwrite() Andrew Morton
2021-05-07 1:06 ` [patch 77/91] arm: print alloc free paths for address in registers Andrew Morton
2021-05-07 1:06 ` [patch 78/91] scripts/spelling.txt: add "overlfow" Andrew Morton
2021-05-07 1:06 ` [patch 79/91] scripts/spelling.txt: add "diabled" typo Andrew Morton
2021-05-07 1:06 ` [patch 80/91] scripts/spelling.txt: add "overflw" Andrew Morton
2021-05-07 1:06 ` [patch 81/91] mm/slab.c: fix spelling mistake "disired" -> "desired" Andrew Morton
2021-05-07 1:06 ` [patch 82/91] include/linux/pgtable.h: few spelling fixes Andrew Morton
2021-05-07 1:06 ` [patch 83/91] kernel/umh.c: fix some spelling mistakes Andrew Morton
2021-05-07 1:06 ` [patch 84/91] kernel/user_namespace.c: fix typos Andrew Morton
2021-05-07 1:06 ` [patch 85/91] kernel/up.c: fix typo Andrew Morton
2021-05-07 1:06 ` [patch 86/91] kernel/sys.c: " Andrew Morton
2021-05-07 1:06 ` [patch 87/91] fs: fat: fix spelling typo of values Andrew Morton
2021-05-07 1:06 ` [patch 88/91] ipc/sem.c: spelling fix Andrew Morton
2021-05-07 1:06 ` [patch 89/91] treewide: remove editor modelines and cruft Andrew Morton
2021-05-07 1:06 ` [patch 90/91] mm: fix typos in comments Andrew Morton
2021-05-07 1:06 ` [patch 91/91] " Andrew Morton
2021-05-07 7:12 ` incoming Linus Torvalds
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