Re: [dpdk-dev] [PATCH 1/5] hash: add new toeplitz hash implementation

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> This patch add a new Toeplitz hash implementation using
> Galios Fields New Instructions (GFNI).
> 
> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
> ---
>  doc/api/doxy-api-index.md |   1 +
>  lib/hash/meson.build      |   1 +
>  lib/hash/rte_thash.c      |  26 ++++++
>  lib/hash/rte_thash.h      |  22 +++++
>  lib/hash/rte_thash_gfni.h | 229 ++++++++++++++++++++++++++++++++++++++++++++++
>  lib/hash/version.map      |   2 +
>  6 files changed, 281 insertions(+)
>  create mode 100644 lib/hash/rte_thash_gfni.h
> 
> diff --git a/doc/api/doxy-api-index.md b/doc/api/doxy-api-index.md
> index 1992107..7549477 100644
> --- a/doc/api/doxy-api-index.md
> +++ b/doc/api/doxy-api-index.md
> @@ -139,6 +139,7 @@ The public API headers are grouped by topics:
>    [hash]               (@ref rte_hash.h),
>    [jhash]              (@ref rte_jhash.h),
>    [thash]              (@ref rte_thash.h),
> +  [thash_gfni]         (@ref rte_thash_gfni.h),
>    [FBK hash]           (@ref rte_fbk_hash.h),
>    [CRC hash]           (@ref rte_hash_crc.h)
> 
> diff --git a/lib/hash/meson.build b/lib/hash/meson.build
> index 9bc5ef9..40444ac 100644
> --- a/lib/hash/meson.build
> +++ b/lib/hash/meson.build
> @@ -7,6 +7,7 @@ headers = files(
>          'rte_hash.h',
>          'rte_jhash.h',
>          'rte_thash.h',
> +        'rte_thash_gfni.h',
>  )
>  indirect_headers += files('rte_crc_arm64.h')
> 
> diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
> index d5a95a6..07447f7 100644
> --- a/lib/hash/rte_thash.c
> +++ b/lib/hash/rte_thash.c
> @@ -11,6 +11,7 @@
>  #include <rte_eal_memconfig.h>
>  #include <rte_log.h>
>  #include <rte_malloc.h>
> +#include <rte_thash_gfni.h>
> 
>  #define THASH_NAME_LEN		64
>  #define TOEPLITZ_HASH_LEN	32
> @@ -88,6 +89,23 @@ struct rte_thash_ctx {
>  	uint8_t		hash_key[0];
>  };
> 
> +uint8_t rte_thash_gfni_supported;

.. = 0;
?

> +
> +void
> +rte_thash_complete_matrix(uint64_t *matrixes, uint8_t *rss_key, int size)
> +{
> +	int i, j;
> +	uint8_t *m = (uint8_t *)matrixes;
> +
> +	for (i = 0; i < size; i++) {
> +		for (j = 0; j < 8; j++) {
> +			m[i * 8 + j] = (rss_key[i] << j)|
> +				(uint8_t)((uint16_t)(rss_key[i + 1]) >>
> +				(8 - j));
> +		}
> +	}
> +}
> +
>  static inline uint32_t
>  get_bit_lfsr(struct thash_lfsr *lfsr)
>  {
> @@ -759,3 +777,11 @@ rte_thash_adjust_tuple(struct rte_thash_ctx *ctx,
> 
>  	return ret;
>  }
> +
> +RTE_INIT(rte_thash_gfni_init)
> +{
> +#ifdef __GFNI__
> +	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_GFNI))
> +		rte_thash_gfni_supported = 1;
> +#endif
> +}
> diff --git a/lib/hash/rte_thash.h b/lib/hash/rte_thash.h
> index 76109fc..e3f1fc6 100644
> --- a/lib/hash/rte_thash.h
> +++ b/lib/hash/rte_thash.h
> @@ -28,6 +28,7 @@ extern "C" {
>  #include <rte_config.h>
>  #include <rte_ip.h>
>  #include <rte_common.h>
> +#include <rte_thash_gfni.h>
> 
>  #if defined(RTE_ARCH_X86) || defined(__ARM_NEON)
>  #include <rte_vect.h>
> @@ -113,6 +114,8 @@ union rte_thash_tuple {
>  };
>  #endif
> 
> +extern uint8_t rte_thash_gfni_supported;
> +
>  /**
>   * Prepare special converted key to use with rte_softrss_be()
>   * @param orig
> @@ -223,6 +226,25 @@ rte_softrss_be(uint32_t *input_tuple, uint32_t input_len,
>  	return ret;
>  }
> 
> +/**
> + * Converts Toeplitz hash key (RSS key) into matrixes required
> + * for GFNI implementation
> + *
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * @param matrixes
> + *  pointer to the memory where matrixes will be writen.
> + *  Note: the size of this memory must be equal to size * 8
> + * @param rss_key
> + *  pointer to the Toeplitz hash key
> + * @param size
> + *  Size of the rss_key in bytes.
> + */
> +__rte_experimental
> +void
> +rte_thash_complete_matrix(uint64_t *matrixes, uint8_t *rss_key, int size);
> +
>  /** @internal Logarithm of minimum size of the RSS ReTa */
>  #define	RTE_THASH_RETA_SZ_MIN	2U
>  /** @internal Logarithm of maximum size of the RSS ReTa */
> diff --git a/lib/hash/rte_thash_gfni.h b/lib/hash/rte_thash_gfni.h
> new file mode 100644
> index 0000000..8f89d7d
> --- /dev/null
> +++ b/lib/hash/rte_thash_gfni.h
> @@ -0,0 +1,229 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2021 Intel Corporation
> + */
> +
> +#ifndef _RTE_THASH_GFNI_H_
> +#define _RTE_THASH_GFNI_H_
> +
> +/**
> + * @file
> + *
> + * Optimized Toeplitz hash functions implementation
> + * using Galois Fields New Instructions.
> + */
> +
> +#include <rte_vect.h>
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#ifdef __GFNI__
> +
> +#define RTE_THASH_FIRST_ITER_MSK	0x0f0f0f0f0f0e0c08
> +#define RTE_THASH_PERM_MSK		0x0f0f0f0f0f0f0f0f
> +#define RTE_THASH_FIRST_ITER_MSK_2	0xf0f0f0f0f0e0c080
> +#define RTE_THASH_PERM_MSK_2		0xf0f0f0f0f0f0f0f0
> +#define RTE_THASH_REWIND_MSK		0x0000000000113377
> +
> +__rte_internal
> +static inline void
> +__rte_thash_xor_reduce(__m512i xor_acc, uint32_t *val_1, uint32_t *val_2)
> +{
> +	__m256i tmp_256_1, tmp_256_2;
> +	__m128i tmp128_1, tmp128_2;
> +	uint64_t tmp_1, tmp_2;
> +
> +	tmp_256_1 = _mm512_castsi512_si256(xor_acc);
> +	tmp_256_2 = _mm512_extracti32x8_epi32(xor_acc, 1);
> +	tmp_256_1 = _mm256_xor_si256(tmp_256_1, tmp_256_2);
> +
> +	tmp128_1 = _mm256_castsi256_si128(tmp_256_1);
> +	tmp128_2 = _mm256_extracti32x4_epi32(tmp_256_1, 1);
> +	tmp128_1 = _mm_xor_si128(tmp128_1, tmp128_2);
> +
> +	tmp_1 = _mm_extract_epi64(tmp128_1, 0);
> +	tmp_2 = _mm_extract_epi64(tmp128_1, 1);
> +	tmp_1 ^= tmp_2;
> +
> +	*val_1 = (uint32_t)tmp_1;
> +	*val_2 = (uint32_t)(tmp_1 >> 32);
> +}
> +
> +__rte_internal
> +static inline __m512i
> +__rte_thash_gfni(uint64_t *mtrx, uint8_t *tuple, uint8_t *secondary_tuple,
> +	int len)

Here and in other fast-path functions:
const uint64_t  *mtrx

> +{
> +	__m512i permute_idx = _mm512_set_epi8(7, 6, 5, 4, 7, 6, 5, 4,
> +						6, 5, 4, 3, 6, 5, 4, 3,
> +						5, 4, 3, 2, 5, 4, 3, 2,
> +						4, 3, 2, 1, 4, 3, 2, 1,
> +						3, 2, 1, 0, 3, 2, 1, 0,
> +						2, 1, 0, -1, 2, 1, 0, -1,
> +						1, 0, -1, -2, 1, 0, -1, -2,
> +						0, -1, -2, -3, 0, -1, -2, -3);
> +
> +	const __m512i rewind_idx = _mm512_set_epi8(0, 0, 0, 0, 0, 0, 0, 0,
> +						0, 0, 0, 0, 0, 0, 0, 0,
> +						0, 0, 0, 0, 0, 0, 0, 0,
> +						0, 0, 0, 0, 0, 0, 0, 0,
> +						0, 0, 0, 0, 0, 0, 0, 0,
> +						0, 0, 0, 59, 0, 0, 0, 59,
> +						0, 0, 59, 58, 0, 0, 59, 58,
> +						0, 59, 58, 57, 0, 59, 58, 57);
> +	const __mmask64 rewind_mask = RTE_THASH_REWIND_MSK;
> +	const __m512i shift_8 = _mm512_set1_epi8(8);
> +	__m512i xor_acc = _mm512_setzero_si512();
> +	__m512i perm_bytes = _mm512_setzero_si512();
> +	__m512i vals, matrixes, tuple_bytes, tuple_bytes_2;
> +	__mmask64 load_mask, permute_mask, permute_mask_2;
> +	int chunk_len = 0, i = 0;
> +	uint8_t mtrx_msk;
> +	const int prepend = 3;
> +
> +	for (; len > 0; len -= 64, tuple += 64) {

What will happen if len < 64?

> +		if (i == 8)
> +			perm_bytes = _mm512_maskz_permutexvar_epi8(rewind_mask,
> +				rewind_idx, perm_bytes);
> +
> +		permute_mask = RTE_THASH_FIRST_ITER_MSK;
> +		load_mask = (len >= 64) ? UINT64_MAX : ((1ULL << len) - 1);
> +		tuple_bytes = _mm512_maskz_loadu_epi8(load_mask, tuple);
> +		if (secondary_tuple) {
> +			permute_mask_2 = RTE_THASH_FIRST_ITER_MSK_2;
> +			tuple_bytes_2 = _mm512_maskz_loadu_epi8(load_mask,
> +				secondary_tuple);
> +		}
> +
> +		chunk_len = __builtin_popcountll(load_mask);
> +		for (i = 0; i < ((chunk_len + prepend) / 8); i++, mtrx += 8) {
> +			perm_bytes = _mm512_mask_permutexvar_epi8(perm_bytes,
> +				permute_mask, permute_idx, tuple_bytes);
> +
> +			if (secondary_tuple)
> +				perm_bytes =
> +					_mm512_mask_permutexvar_epi8(perm_bytes,
> +					permute_mask_2, permute_idx,
> +					tuple_bytes_2);
> +
> +			matrixes = _mm512_maskz_loadu_epi64(UINT8_MAX, mtrx);
> +			vals = _mm512_gf2p8affine_epi64_epi8(perm_bytes,
> +				matrixes, 0);
> +
> +			xor_acc = _mm512_xor_si512(xor_acc, vals);
> +			permute_idx = _mm512_add_epi8(permute_idx, shift_8);
> +			permute_mask = RTE_THASH_PERM_MSK;
> +			if (secondary_tuple)
> +				permute_mask_2 = RTE_THASH_PERM_MSK_2;
> +		}
> +	}
> +
> +	int rest_len = (chunk_len + prepend) % 8;
> +	if (rest_len != 0) {
> +		mtrx_msk = (1 << (rest_len % 8)) - 1;
> +		matrixes = _mm512_maskz_loadu_epi64(mtrx_msk, mtrx);
> +		if (i == 8) {
> +			perm_bytes = _mm512_maskz_permutexvar_epi8(rewind_mask,
> +				rewind_idx, perm_bytes);
> +		} else {
> +			perm_bytes = _mm512_mask_permutexvar_epi8(perm_bytes,
> +				permute_mask, permute_idx, tuple_bytes);
> +
> +			if (secondary_tuple)
> +				perm_bytes =
> +					_mm512_mask_permutexvar_epi8(
> +					perm_bytes, permute_mask_2,
> +					permute_idx, tuple_bytes_2);
> +		}
> +
> +		vals = _mm512_gf2p8affine_epi64_epi8(perm_bytes, matrixes, 0);
> +		xor_acc = _mm512_xor_si512(xor_acc, vals);
> +	}
> +
> +	return xor_acc;
> +}
> +
> +/**
> + * Calculate Toeplitz hash.
> + *
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * @param m
> + *  Pointer to the matrices generated from the corresponding
> + *  RSS hash key using rte_thash_complete_matrix().
> + * @param tuple
> + *  Pointer to the data to be hashed. Data must be in network byte order.
> + * @param len
> + *  Length of the data to be hashed.
> + * @return
> + *  Calculated Toeplitz hash value.
> + */
> +__rte_experimental
> +static inline uint32_t
> +rte_thash_gfni(uint64_t *m, uint8_t *tuple, int len)
> +{
> +	uint32_t val, val_zero;
> +
> +	__m512i xor_acc = __rte_thash_gfni(m, tuple, NULL, len);
> +	__rte_thash_xor_reduce(xor_acc, &val, &val_zero);
> +
> +	return val;
> +}
> +
> +/**
> + * Calculate Toeplitz hash for two independent data buffers.
> + *
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * @param m
> + *  Pointer to the matrices generated from the corresponding
> + *  RSS hash key using rte_thash_complete_matrix().
> + * @param tuple_1
> + *  Pointer to the data to be hashed. Data must be in network byte order.
> + * @param tuple_2
> + *  Pointer to the data to be hashed. Data must be in network byte order.
> + * @param len
> + *  Length of the largest data buffer to be hashed.
> + * @param val_1
> + *  Pointer to uint32_t where to put calculated Toeplitz hash value for
> + *  the first tuple.
> + * @param val_2
> + *  Pointer to uint32_t where to put calculated Toeplitz hash value for
> + *  the second tuple.
> + */
> +__rte_experimental
> +static inline void
> +rte_thash_gfni_x2(uint64_t *mtrx, uint8_t *tuple_1, uint8_t *tuple_2, int len,
> +	uint32_t *val_1, uint32_t *val_2)

Why just two?
Why not uint8_t *tuple[]
?

> +{
> +	__m512i xor_acc = __rte_thash_gfni(mtrx, tuple_1, tuple_2, len);
> +	__rte_thash_xor_reduce(xor_acc, val_1, val_2);
> +}
> +
> +#else /* __GFNI__ */
> +
> +static inline uint32_t
> +rte_thash_gfni(uint64_t *mtrx __rte_unused, uint8_t *key __rte_unused,
> +	int len __rte_unused)
> +{
> +	return 0;
> +}
> +
> +static inline void
> +rte_thash_gfni_x2(uint64_t *mtrx __rte_unused, uint8_t *tuple_1 __rte_unused,
> +	uint8_t *tuple_2 __rte_unused, int len __rte_unused,
> +	uint32_t *val_1 __rte_unused, uint32_t *val_2 __rte_unused)
> +{
> +

That seems inconsistent with dummy rte_thash_gfni() above.
Should be:
*val_1  = 0; *val_2 = 0; 
I think.

> +}
> +
> +#endif
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_THASH_GFNI_H_ */
> diff --git a/lib/hash/version.map b/lib/hash/version.map
> index ce4309a..cecf922 100644
> --- a/lib/hash/version.map
> +++ b/lib/hash/version.map
> @@ -39,10 +39,12 @@ EXPERIMENTAL {
>  	rte_hash_rcu_qsbr_add;
>  	rte_thash_add_helper;
>  	rte_thash_adjust_tuple;
> +	rte_thash_complete_matrix;
>  	rte_thash_find_existing;
>  	rte_thash_free_ctx;
>  	rte_thash_get_complement;
>  	rte_thash_get_helper;
>  	rte_thash_get_key;
> +	rte_thash_gfni_supported;
>  	rte_thash_init_ctx;
>  };
> --
> 2.7.4