From 71ae8aac3e198c6f3577cb7ad3a17f6128e97bfa Mon Sep 17 00:00:00 2001 From: Francesco Fusco Date: Thu, 12 Dec 2013 16:09:05 +0100 Subject: lib: introduce arch optimized hash library We introduce a new hashing library that is meant to be used in the contexts where speed is more important than uniformity of the hashed values. The hash library leverages architecture specific implementation to achieve high performance and fall backs to jhash() for the generic case. On Intel-based x86 architectures, the library can exploit the crc32l instruction, part of the Intel SSE4.2 instruction set, if the instruction is supported by the processor. This implementation is twice as fast as the jhash() implementation on an i7 processor. Additional architectures, such as Arm64 provide instructions for accelerating the computation of CRC, so they could be added as well in follow-up work. Signed-off-by: Francesco Fusco Signed-off-by: Daniel Borkmann Signed-off-by: Thomas Graf Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller --- lib/Makefile | 2 +- lib/hash.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-) create mode 100644 lib/hash.c (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index a459c31e8c6b..d0f79c547d97 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -26,7 +26,7 @@ obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \ bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \ gcd.o lcm.o list_sort.o uuid.o flex_array.o iovec.o clz_ctz.o \ bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \ - percpu-refcount.o percpu_ida.o + percpu-refcount.o percpu_ida.o hash.o obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o obj-y += kstrtox.o diff --git a/lib/hash.c b/lib/hash.c new file mode 100644 index 000000000000..b89f06a2d606 --- /dev/null +++ b/lib/hash.c @@ -0,0 +1,38 @@ +/* General purpose hashing library + * + * That's a start of a kernel hashing library, which can be extended + * with further algorithms in future. arch_fast_hash{2,}() will + * eventually resolve to an architecture optimized implementation. + * + * Copyright 2013 Francesco Fusco + * Copyright 2013 Daniel Borkmann + * Copyright 2013 Thomas Graf + * Licensed under the GNU General Public License, version 2.0 (GPLv2) + */ + +#include +#include + +static struct fast_hash_ops arch_hash_ops __read_mostly = { + .hash = jhash, + .hash2 = jhash2, +}; + +u32 arch_fast_hash(const void *data, u32 len, u32 seed) +{ + return arch_hash_ops.hash(data, len, seed); +} +EXPORT_SYMBOL_GPL(arch_fast_hash); + +u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed) +{ + return arch_hash_ops.hash2(data, len, seed); +} +EXPORT_SYMBOL_GPL(arch_fast_hash2); + +static int __init hashlib_init(void) +{ + setup_arch_fast_hash(&arch_hash_ops); + return 0; +} +early_initcall(hashlib_init); -- cgit v1.2.3