Hi Pablo, > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Pablo de Lara > Sent: Tuesday, May 05, 2015 3:44 PM > To: dev at dpdk.org > Subject: [dpdk-dev] [PATCH v3 3/6] hash: update jhash function with the > latest available > > Jenkins hash function was developed originally in 1996, > and was integrated in first versions of DPDK. > The function has been improved in 2006, > achieving up to 60% better performance, compared to the original one. > > This patch integrates that code into the rte_jhash library. > > Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com> > --- > lib/librte_hash/rte_jhash.h | 261 > +++++++++++++++++++++++++++++++------------ > 1 files changed, 188 insertions(+), 73 deletions(-) > > diff --git a/lib/librte_hash/rte_jhash.h b/lib/librte_hash/rte_jhash.h > index a4bf5a1..0e96b7c 100644 > --- a/lib/librte_hash/rte_jhash.h > +++ b/lib/librte_hash/rte_jhash.h > @@ -1,7 +1,7 @@ > /*- > * BSD LICENSE > * > - * Copyright(c) 2010-2014 Intel Corporation. All rights reserved. > + * Copyright(c) 2010-2015 Intel Corporation. All rights reserved. > * All rights reserved. > * > * Redistribution and use in source and binary forms, with or without > @@ -45,38 +45,68 @@ extern "C" { > #endif > > #include <stdint.h> > +#include <string.h> > +#include <rte_byteorder.h> > > /* jhash.h: Jenkins hash support. > * > - * Copyright (C) 1996 Bob Jenkins (bob_jenkins at burtleburtle.net) > + * Copyright (C) 2006 Bob Jenkins (bob_jenkins at burtleburtle.net) > * > * http://burtleburtle.net/bob/hash/ > * > * These are the credits from Bob's sources: > * > - * lookup2.c, by Bob Jenkins, December 1996, Public Domain. > - * hash(), hash2(), hash3, and mix() are externally useful functions. > - * Routines to test the hash are included if SELF_TEST is defined. > - * You can use this free for any purpose. It has no warranty. > + * lookup3.c, by Bob Jenkins, May 2006, Public Domain. > + * > + * These are functions for producing 32-bit hashes for hash table lookup. > + * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() > + * are externally useful functions. Routines to test the hash are included > + * if SELF_TEST is defined. You can use this free for any purpose. It's in > + * the public domain. It has no warranty. > * > * $FreeBSD$ > */ > > +#define rot(x, k) (((x) << (k)) | ((x) >> (32-(k)))) > + > /** @internal Internal function. NOTE: Arguments are modified. */ > #define __rte_jhash_mix(a, b, c) do { \ > - a -= b; a -= c; a ^= (c>>13); \ > - b -= c; b -= a; b ^= (a<<8); \ > - c -= a; c -= b; c ^= (b>>13); \ > - a -= b; a -= c; a ^= (c>>12); \ > - b -= c; b -= a; b ^= (a<<16); \ > - c -= a; c -= b; c ^= (b>>5); \ > - a -= b; a -= c; a ^= (c>>3); \ > - b -= c; b -= a; b ^= (a<<10); \ > - c -= a; c -= b; c ^= (b>>15); \ > + a -= c; a ^= rot(c, 4); c += b; \ > + b -= a; b ^= rot(a, 6); a += c; \ > + c -= b; c ^= rot(b, 8); b += a; \ > + a -= c; a ^= rot(c, 16); c += b; \ > + b -= a; b ^= rot(a, 19); a += c; \ > + c -= b; c ^= rot(b, 4); b += a; \ > +} while (0) > + > +#define __rte_jhash_final(a, b, c) do { \ > + c ^= b; c -= rot(b, 14); \ > + a ^= c; a -= rot(c, 11); \ > + b ^= a; b -= rot(a, 25); \ > + c ^= b; c -= rot(b, 16); \ > + a ^= c; a -= rot(c, 4); \ > + b ^= a; b -= rot(a, 14); \ > + c ^= b; c -= rot(b, 24); \ > } while (0) > > /** The golden ratio: an arbitrary value. */ > -#define RTE_JHASH_GOLDEN_RATIO 0x9e3779b9 > +#define RTE_JHASH_GOLDEN_RATIO 0xdeadbeef > + > +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN > +#define RTE_JHASH_BYTE0_SHIFT 0 > +#define RTE_JHASH_BYTE1_SHIFT 8 > +#define RTE_JHASH_BYTE2_SHIFT 16 > +#define RTE_JHASH_BYTE3_SHIFT 24 > +#else > +#define RTE_JHASH_BYTE0_SHIFT 24 > +#define RTE_JHASH_BYTE1_SHIFT 16 > +#define RTE_JHASH_BYTE2_SHIFT 8 > +#define RTE_JHASH_BYTE3_SHIFT 0 > +#endif > + > +#define LOWER8b_MASK rte_le_to_cpu_32(0xff) > +#define LOWER16b_MASK rte_le_to_cpu_32(0xffff) > +#define LOWER24b_MASK rte_le_to_cpu_32(0xffffff) > > /** > * The most generic version, hashes an arbitrary sequence > @@ -95,42 +125,119 @@ extern "C" { > static inline uint32_t > rte_jhash(const void *key, uint32_t length, uint32_t initval) > { > - uint32_t a, b, c, len; > - const uint8_t *k = (const uint8_t *)key; > - const uint32_t *k32 = (const uint32_t *)key; > + uint32_t a, b, c; > + union { > + const void *ptr; > + size_t i; > + } u; > > - len = length; > - a = b = RTE_JHASH_GOLDEN_RATIO; > - c = initval; > + /* Set up the internal state */ > + a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + initval; > > - while (len >= 12) { > - a += k32[0]; > - b += k32[1]; > - c += k32[2]; > + u.ptr = key; > > - __rte_jhash_mix(a,b,c); > + /* Check key alignment. For x86 architecture, first case is always > optimal */ > + if (!strcmp(RTE_ARCH,"x86_64") || !strcmp(RTE_ARCH,"i686") || (u.i & > 0x3) == 0) {
Wonder why strcmp(), why not something like: 'if defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_64)' as in all other places? Another question what would be in case of RTE_ARCH="x86_x32"? Konstantin > + const uint32_t *k = (const uint32_t *)key; > > - k += (3 * sizeof(uint32_t)), k32 += 3; > - len -= (3 * sizeof(uint32_t)); > - } > + while (length > 12) { > + a += k[0]; > + b += k[1]; > + c += k[2]; > > - c += length; > - switch (len) { > - case 11: c += ((uint32_t)k[10] << 24); > - case 10: c += ((uint32_t)k[9] << 16); > - case 9 : c += ((uint32_t)k[8] << 8); > - case 8 : b += ((uint32_t)k[7] << 24); > - case 7 : b += ((uint32_t)k[6] << 16); > - case 6 : b += ((uint32_t)k[5] << 8); > - case 5 : b += k[4]; > - case 4 : a += ((uint32_t)k[3] << 24); > - case 3 : a += ((uint32_t)k[2] << 16); > - case 2 : a += ((uint32_t)k[1] << 8); > - case 1 : a += k[0]; > - default: break; > - }; > + __rte_jhash_mix(a, b, c); > + > + k += 3; > + length -= 12; > + } > + > + switch (length) { > + case 12: > + c += k[2]; b += k[1]; a += k[0]; break; > + case 11: > + c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break; > + case 10: > + c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break; > + case 9: > + c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break; > + case 8: > + b += k[1]; a += k[0]; break; > + case 7: > + b += k[1] & LOWER24b_MASK; a += k[0]; break; > + case 6: > + b += k[1] & LOWER16b_MASK; a += k[0]; break; > + case 5: > + b += k[1] & LOWER8b_MASK; a += k[0]; break; > + case 4: > + a += k[0]; break; > + case 3: > + a += k[0] & LOWER24b_MASK; break; > + case 2: > + a += k[0] & LOWER16b_MASK; break; > + case 1: > + a += k[0] & LOWER8b_MASK; break; > + /* zero length strings require no mixing */ > + case 0: > + return c; > + }; > + } else { > + const uint8_t *k = (const uint8_t *)key; > + > + /* all but the last block: affect some 32 bits of (a, b, c) */ > + while (length > 12) { > + a += ((uint32_t)k[0]) << RTE_JHASH_BYTE0_SHIFT; > + a += ((uint32_t)k[1]) << RTE_JHASH_BYTE1_SHIFT; > + a += ((uint32_t)k[2]) << RTE_JHASH_BYTE2_SHIFT; > + a += ((uint32_t)k[3]) << RTE_JHASH_BYTE3_SHIFT; > + b += ((uint32_t)k[4]) << RTE_JHASH_BYTE0_SHIFT; > + b += ((uint32_t)k[5]) << RTE_JHASH_BYTE1_SHIFT; > + b += ((uint32_t)k[6]) << RTE_JHASH_BYTE2_SHIFT; > + b += ((uint32_t)k[7]) << RTE_JHASH_BYTE3_SHIFT; > + c += ((uint32_t)k[8]) << RTE_JHASH_BYTE0_SHIFT; > + c += ((uint32_t)k[9]) << RTE_JHASH_BYTE1_SHIFT; > + c += ((uint32_t)k[10]) << RTE_JHASH_BYTE2_SHIFT; > + c += ((uint32_t)k[11]) << RTE_JHASH_BYTE3_SHIFT; > + > + __rte_jhash_mix(a, b, c); > + > + k += 12; > + length -= 12; > + } > + > + /* last block: affect all 32 bits of (c) */ > + /* all the case statements fall through */ > + switch (length) { > + case 12: > + c += ((uint32_t)k[11]) << RTE_JHASH_BYTE3_SHIFT; > + case 11: > + c += ((uint32_t)k[10]) << RTE_JHASH_BYTE2_SHIFT; > + case 10: > + c += ((uint32_t)k[9]) << RTE_JHASH_BYTE1_SHIFT; > + case 9: > + c += ((uint32_t)k[8]) << RTE_JHASH_BYTE0_SHIFT; > + case 8: > + b += ((uint32_t)k[7]) << RTE_JHASH_BYTE3_SHIFT; > + case 7: > + b += ((uint32_t)k[6]) << RTE_JHASH_BYTE2_SHIFT; > + case 6: > + b += ((uint32_t)k[5]) << RTE_JHASH_BYTE1_SHIFT; > + case 5: > + b += ((uint32_t)k[4]) << RTE_JHASH_BYTE0_SHIFT; > + case 4: > + a += ((uint32_t)k[3]) << RTE_JHASH_BYTE3_SHIFT; > + case 3: > + a += ((uint32_t)k[2]) << RTE_JHASH_BYTE2_SHIFT; > + case 2: > + a += ((uint32_t)k[1]) << RTE_JHASH_BYTE1_SHIFT; > + case 1: > + a += ((uint32_t)k[0]) << RTE_JHASH_BYTE0_SHIFT; > + break; > + case 0: > + return c; > + } > + } > > - __rte_jhash_mix(a,b,c); > + __rte_jhash_final(a, b, c); > > return c; > } > @@ -151,33 +258,51 @@ rte_jhash(const void *key, uint32_t length, uint32_t > initval) > static inline uint32_t > rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval) > { > - uint32_t a, b, c, len; > + uint32_t a, b, c; > > - a = b = RTE_JHASH_GOLDEN_RATIO; > - c = initval; > - len = length; > + /* Set up the internal state */ > + a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length) << 2) + > initval; > > - while (len >= 3) { > + /* Handle most of the key */ > + while (length > 3) { > a += k[0]; > b += k[1]; > c += k[2]; > + > __rte_jhash_mix(a, b, c); > - k += 3; len -= 3; > - } > > - c += length * 4; > + k += 3; > + length -= 3; > + } > > - switch (len) { > - case 2 : b += k[1]; > - case 1 : a += k[0]; > - default: break; > + /* Handle the last 3 uint32_t's */ > + switch (length) { > + case 3: > + c += k[2]; > + case 2: > + b += k[1]; > + case 1: > + a += k[0]; > + __rte_jhash_final(a, b, c); > + /* case 0: nothing left to add */ > + case 0: > + break; > }; > > - __rte_jhash_mix(a,b,c); > - > return c; > } > > +static inline uint32_t > +__rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval) > +{ > + a += RTE_JHASH_GOLDEN_RATIO + initval; > + b += RTE_JHASH_GOLDEN_RATIO + initval; > + c += RTE_JHASH_GOLDEN_RATIO + initval; > + > + __rte_jhash_final(a, b, c); > + > + return c; > +} > > /** > * A special ultra-optimized versions that knows it is hashing exactly > @@ -197,17 +322,7 @@ rte_jhash2(const uint32_t *k, uint32_t length, uint32_t > initval) > static inline uint32_t > rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval) > { > - a += RTE_JHASH_GOLDEN_RATIO; > - b += RTE_JHASH_GOLDEN_RATIO; > - c += initval; > - > - __rte_jhash_mix(a, b, c); > - > - /* > - * NOTE: In particular the "c += length; __rte_jhash_mix(a,b,c);" > - * normally done at the end is not done here. > - */ > - return c; > + return __rte_jhash_3words(a + 12, b + 12, c + 12, initval); > } > > /** > @@ -226,7 +341,7 @@ rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, > uint32_t initval) > static inline uint32_t > rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval) > { > - return rte_jhash_3words(a, b, 0, initval); > + return __rte_jhash_3words(a + 8, b + 8, 8, initval); > } > > /** > @@ -243,7 +358,7 @@ rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval) > static inline uint32_t > rte_jhash_1word(uint32_t a, uint32_t initval) > { > - return rte_jhash_3words(a, 0, 0, initval); > + return __rte_jhash_3words(a + 4, 4, 4, initval); > } > > #ifdef __cplusplus > -- > 1.7.4.1