[dpdk-dev] [PATCH 2/5] hash: enable gfni thash implementation

[Ananyev, Konstantin]

> This patch enables new GFNI Toeplitz hash in
> predictable RSS library.
> 
> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin at intel.com>
> ---
>  lib/hash/rte_thash.c | 43 +++++++++++++++++++++++++++++++++++++++----
>  lib/hash/rte_thash.h | 19 +++++++++++++++++++
>  lib/hash/version.map |  1 +
>  3 files changed, 59 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
> index 07447f7..86a0e96 100644
> --- a/lib/hash/rte_thash.c
> +++ b/lib/hash/rte_thash.c
> @@ -86,6 +86,8 @@ struct rte_thash_ctx {
>  	uint32_t	reta_sz_log;	/** < size of the RSS ReTa in bits */
>  	uint32_t	subtuples_nb;	/** < number of subtuples */
>  	uint32_t	flags;
> +	uint64_t	*matrices;

Comment, what is that, etc.

> +	/**< rte_thash_complete_matrix generated matrices */
>  	uint8_t		hash_key[0];
>  };
> 
> @@ -253,12 +255,25 @@ rte_thash_init_ctx(const char *name, uint32_t key_len, uint32_t reta_sz,
>  			ctx->hash_key[i] = rte_rand();
>  	}
> 
> +	if (rte_thash_gfni_supported) {

I think it should be:
if (rte_thash_gfni_supported && rte_vect_get_max_simd_bitwidth() >= RTE_VECT_SIMD_512)


> +		ctx->matrices = rte_zmalloc(NULL, key_len * sizeof(uint64_t),
> +			RTE_CACHE_LINE_SIZE);

You can do it probably before allocation ctx, at the same place where te is allocated.
Might be a bit nicer.

> +		if (ctx->matrices == NULL)

		RTE_LOG(ERR, ...);
		rte_ernno = ENOMEM;

> +			goto free_ctx;
> +
> +		rte_thash_complete_matrix(ctx->matrices, ctx->hash_key,
> +			key_len);
> +	}
> +
>  	te->data = (void *)ctx;
>  	TAILQ_INSERT_TAIL(thash_list, te, next);
> 
>  	rte_mcfg_tailq_write_unlock();
> 
>  	return ctx;
> +
> +free_ctx:
> +	rte_free(ctx);
>  free_te:
>  	rte_free(te);
>  exit:
> @@ -372,6 +387,10 @@ generate_subkey(struct rte_thash_ctx *ctx, struct thash_lfsr *lfsr,
>  			set_bit(ctx->hash_key, get_rev_bit_lfsr(lfsr), i);
>  	}
> 
> +	if (rte_thash_gfni_supported)

Here and in data-path functions, I think it would be better:
if (ctx->matrices != NULL)
> +		rte_thash_complete_matrix(ctx->matrices, ctx->hash_key,
> +			ctx->key_len);
> +
>  	return 0;
>  }
> 
> @@ -628,6 +647,16 @@ rte_thash_get_key(struct rte_thash_ctx *ctx)
>  	return ctx->hash_key;
>  }
> 
> +const uint64_t *
> +rte_thash_get_gfni_matrices(struct rte_thash_ctx *ctx)
> +{
> +	if (rte_thash_gfni_supported)
> +		return ctx->matrices;

Why not just always:
return ctx->matices;
?

> +
> +	rte_errno = ENOTSUP;
> +	return NULL;
> +}
> +
>  static inline uint8_t
>  read_unaligned_byte(uint8_t *ptr, unsigned int len, unsigned int offset)
>  {
> @@ -739,11 +768,17 @@ rte_thash_adjust_tuple(struct rte_thash_ctx *ctx,
>  	attempts = RTE_MIN(attempts, 1U << (h->tuple_len - ctx->reta_sz_log));
> 
>  	for (i = 0; i < attempts; i++) {
> -		for (j = 0; j < (tuple_len / 4); j++)
> -			tmp_tuple[j] =
> -				rte_be_to_cpu_32(*(uint32_t *)&tuple[j * 4]);
> +		if (rte_thash_gfni_supported)
if (ctx->matrices)

> +			hash = rte_thash_gfni(ctx->matrices, tuple, tuple_len);
> +		else {
> +			for (j = 0; j < (tuple_len / 4); j++)
> +				tmp_tuple[j] =
> +					rte_be_to_cpu_32(
> +						*(uint32_t *)&tuple[j * 4]);
> +
> +			hash = rte_softrss(tmp_tuple, tuple_len / 4, hash_key);
> +		}
> 
> -		hash = rte_softrss(tmp_tuple, tuple_len / 4, hash_key);
>  		adj_bits = rte_thash_get_complement(h, hash, desired_value);
> 
>  		/*
> diff --git a/lib/hash/rte_thash.h b/lib/hash/rte_thash.h
> index e3f1fc6..6e6861c 100644
> --- a/lib/hash/rte_thash.h
> +++ b/lib/hash/rte_thash.h
> @@ -410,6 +410,25 @@ const uint8_t *
>  rte_thash_get_key(struct rte_thash_ctx *ctx);
> 
>  /**
> + * Get a pointer to the toeplitz hash matrices contained in the context.
> + * These matrices could be used with fast toeplitz hash implementation if
> + * CPU supports GFNI.
> + * Matrices changes after each addition of a helper.
> + *
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * @param ctx
> + *  Thash context
> + * @return
> + *  A pointer to the toeplitz hash key matrices on success
> + *  NULL if GFNI is not supported.
> + */
> +__rte_experimental
> +const uint64_t *
> +rte_thash_get_gfni_matrices(struct rte_thash_ctx *ctx);
> +
> +/**
>   * Function prototype for the rte_thash_adjust_tuple
>   * to check if adjusted tuple could be used.
>   * Generally it is some kind of lookup function to check
> diff --git a/lib/hash/version.map b/lib/hash/version.map
> index cecf922..3eda695 100644
> --- a/lib/hash/version.map
> +++ b/lib/hash/version.map
> @@ -43,6 +43,7 @@ EXPERIMENTAL {
>  	rte_thash_find_existing;
>  	rte_thash_free_ctx;
>  	rte_thash_get_complement;
> +	rte_thash_get_gfni_matrices;
>  	rte_thash_get_helper;
>  	rte_thash_get_key;
>  	rte_thash_gfni_supported;
> --
> 2.7.4