Re: [dpdk-dev] [PATCH v4 1/3] hash: add predictable RSS API

["Wang, Yipeng1" <yipeng1.wang@intel.com>]

> -----Original Message-----
> From: Medvedkin, Vladimir <vladimir.medvedkin@intel.com>
> Sent: Tuesday, April 13, 2021 6:20 AM
> To: dev@dpdk.org
> Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Chilikin, Andrey
> <andrey.chilikin@intel.com>; Kinsella, Ray <ray.kinsella@intel.com>; Wang,
> Yipeng1 <yipeng1.wang@intel.com>; Gobriel, Sameh
> <sameh.gobriel@intel.com>; Richardson, Bruce
> <bruce.richardson@intel.com>
> Subject: [PATCH v4 1/3] hash: add predictable RSS API
> 
> This patch adds predictable RSS API.
> It is based on the idea of searching partial Toeplitz hash collisions.
> 
> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
> ---
>  lib/librte_hash/meson.build |   3 +-
>  lib/librte_hash/rte_thash.c | 109 ++++++++++++++++++++++++
> lib/librte_hash/rte_thash.h | 198
> ++++++++++++++++++++++++++++++++++++++++++++
>  lib/librte_hash/version.map |   8 ++
>  4 files changed, 317 insertions(+), 1 deletion(-)  create mode 100644
> lib/librte_hash/rte_thash.c
> 
> diff --git a/lib/librte_hash/meson.build b/lib/librte_hash/meson.build index
> 242859f..3546014 100644
> --- a/lib/librte_hash/meson.build
> +++ b/lib/librte_hash/meson.build
> @@ -8,6 +8,7 @@ headers = files('rte_fbk_hash.h',
>  	'rte_thash.h')
>  indirect_headers += files('rte_crc_arm64.h')
> 
> -sources = files('rte_cuckoo_hash.c', 'rte_fbk_hash.c')
> +sources = files('rte_cuckoo_hash.c', 'rte_fbk_hash.c', 'rte_thash.c')
> +deps += ['net']
>  deps += ['ring']
>  deps += ['rcu']
> diff --git a/lib/librte_hash/rte_thash.c b/lib/librte_hash/rte_thash.c new file
> mode 100644 index 0000000..1325678
> --- /dev/null
> +++ b/lib/librte_hash/rte_thash.c
> @@ -0,0 +1,109 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2021 Intel Corporation
> + */
> +
> +#include <rte_thash.h>
> +#include <rte_tailq.h>
> +#include <rte_random.h>
> +#include <rte_memcpy.h>
> +#include <rte_errno.h>
> +#include <rte_eal.h>
> +#include <rte_eal_memconfig.h>
> +#include <rte_malloc.h>
> +
> +#define THASH_NAME_LEN		64
> +
> +struct thash_lfsr {
> +	uint32_t	ref_cnt;
> +	uint32_t	poly;
> +	/**< polynomial associated with the lfsr */
> +	uint32_t	rev_poly;
> +	/**< polynomial to generate the sequence in reverse direction */
> +	uint32_t	state;
> +	/**< current state of the lfsr */
> +	uint32_t	rev_state;
> +	/**< current state of the lfsr for reverse direction */
> +	uint32_t	deg;	/**< polynomial degree*/
> +	uint32_t	bits_cnt;  /**< number of bits generated by lfsr*/
> +};
> +
> +struct rte_thash_subtuple_helper {
> +	char	name[THASH_NAME_LEN];	/** < Name of subtuple
> configuration */
> +	LIST_ENTRY(rte_thash_subtuple_helper)	next;
> +	struct thash_lfsr	*lfsr;
> +	uint32_t	offset;		/** < Offset of the m-sequence */
> +	uint32_t	len;		/** < Length of the m-sequence */
> +	uint32_t	tuple_offset;	/** < Offset in bits of the subtuple */
> +	uint32_t	tuple_len;	/** < Length in bits of the subtuple
> */
> +	uint32_t	lsb_msk;	/** < (1 << reta_sz_log) - 1 */
> +	__extension__ uint32_t	compl_table[0] __rte_cache_aligned;
> +	/** < Complementary table */
> +};
> +
> +struct rte_thash_ctx {
> +	char		name[THASH_NAME_LEN];
> +	LIST_HEAD(, rte_thash_subtuple_helper) head;
> +	uint32_t	key_len;	/** < Length of the NIC RSS hash key
> */
> +	uint32_t	reta_sz_log;	/** < size of the RSS ReTa in bits */
> +	uint32_t	subtuples_nb;	/** < number of subtuples */
> +	uint32_t	flags;
> +	uint8_t		hash_key[0];
> +};
> +
> +struct rte_thash_ctx *
> +rte_thash_init_ctx(const char *name __rte_unused,
> +	uint32_t key_len __rte_unused, uint32_t reta_sz __rte_unused,
> +	uint8_t *key __rte_unused, uint32_t flags __rte_unused) {
> +	return NULL;
> +}
> +
> +struct rte_thash_ctx *
> +rte_thash_find_existing(const char *name __rte_unused) {
> +	return NULL;
> +}
> +
> +void
> +rte_thash_free_ctx(struct rte_thash_ctx *ctx __rte_unused) { }
> +
> +int
> +rte_thash_add_helper(struct rte_thash_ctx *ctx __rte_unused,
> +	const char *name __rte_unused, uint32_t len __rte_unused,
> +	uint32_t offset __rte_unused)
> +{
> +	return 0;
> +}
> +
> +struct rte_thash_subtuple_helper *
> +rte_thash_get_helper(struct rte_thash_ctx *ctx __rte_unused,
> +	const char *name __rte_unused)
> +{
> +	return NULL;
> +}
> +
> +uint32_t
> +rte_thash_get_complement(struct rte_thash_subtuple_helper *h
> __rte_unused,
> +	uint32_t hash __rte_unused, uint32_t desired_hash __rte_unused) {
> +	return 0;
> +}
> +
> +const uint8_t *
> +rte_thash_get_key(struct rte_thash_ctx *ctx __rte_unused) {
> +	return NULL;
> +}
> +
> +int
> +rte_thash_adjust_tuple(struct rte_thash_ctx *ctx __rte_unused,
> +	struct rte_thash_subtuple_helper *h __rte_unused,
> +	uint8_t *tuple __rte_unused, unsigned int tuple_len __rte_unused,
> +	uint32_t desired_value __rte_unused,
> +	unsigned int attempts __rte_unused,
> +	rte_thash_check_tuple_t fn __rte_unused, void *userdata
> __rte_unused)
> +{
> +	return 0;
> +}
> diff --git a/lib/librte_hash/rte_thash.h b/lib/librte_hash/rte_thash.h index
> 061efa2..f3e05fc 100644
> --- a/lib/librte_hash/rte_thash.h
> +++ b/lib/librte_hash/rte_thash.h
> @@ -1,5 +1,6 @@
>  /* SPDX-License-Identifier: BSD-3-Clause
>   * Copyright(c) 2015-2019 Vladimir Medvedkin <medvedkinv@gmail.com>
> + * Copyright(c) 2021 Intel Corporation
>   */
> 
>  #ifndef _RTE_THASH_H
> @@ -222,6 +223,203 @@ rte_softrss_be(uint32_t *input_tuple, uint32_t
> input_len,
>  	return ret;
>  }
> 
> +/** @internal Minimum size of the RSS ReTa */
[Wang, Yipeng] Logarithm of minimum size.
> +#define	RTE_THASH_RETA_SZ_MIN	2U
> +/** @internal Maximum size of the RSS ReTa */
> +#define	RTE_THASH_RETA_SZ_MAX	16U
> +
> +/**
> + * LFSR will ignore if generated m-sequence has more than 2^n -1 bits
[Wang, Yipeng] Have you mentioned what is n here in the comment?
> +*/
<snip>
>  };
> --
> 2.7.4

[Wang, Yipeng] 
Acked-by: Yipeng Wang <yipeng1.wang@intel.com>