Re: [dpdk-dev] [PATCH v5] Add toeplitz hash algorithm used by RSS

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Jun 19, 2015 at 01:31:13PM -0400, Vladimir Medvedkin wrote:
> Software implementation of the Toeplitz hash function used by RSS.
> Can be used either for packet distribution on single queue NIC
> or for simulating of RSS computation on specific NIC (for example
> after GRE header decapsulating).
> 
> v5 changes
> - Fix errors reported by checkpatch.pl
> 
> v4 changes
> - Fix copyright
> - rename bswap_mask constant, add rte_ prefix
> - change rte_ipv[46]_tuple struct
> - change rte_thash_load_v6_addr prototype
> 
> v3 changes
> - Rework API to be more generic
> - Add sctp_tag into tuple
> 
> v2 changes
> - Add ipv6 support
> - Various style fixes
> 
> Signed-off-by: Vladimir Medvedkin <medvedkinv@gmail.com>
> ---
>  lib/librte_hash/Makefile    |   1 +
>  lib/librte_hash/rte_thash.h | 207 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 208 insertions(+)
>  create mode 100644 lib/librte_hash/rte_thash.h
>
<snip>
> +static const __m128i rte_thash_ipv6_bswap_mask = {
> +		0x0405060700010203, 0x0C0D0E0F08090A0B};
> +
> +#define RTE_THASH_V4_L3	 2	/*calculate hash of ipv4 header only*/
> +#define RTE_THASH_V4_L4	 3	/*calculate hash of ipv4 + transport headers*/
> +#define RTE_THASH_V6_L3	 8	/*calculate hash of ipv6 header only */
> +#define RTE_THASH_V6_L4	 9	/*calculate hash of ipv6 + transport headers */
> +

Comment as on V4 patch - add LEN to name to make it clear they are lengths
in quadwords.

> +/**
> + * IPv4 tuple
> + * addreses and ports/sctp_tag have to be CPU byte order
> + */
> +struct rte_ipv4_tuple {
> +	uint32_t	src_addr;
> +	uint32_t	dst_addr;
> +	union {
> +		struct {
> +			uint16_t dport;
> +			uint16_t sport;
> +		};
> +		uint32_t        sctp_tag;
> +	};
> +};
> +
> +/**
> + * IPv6 tuple
> + * Addresses have to be filled by rte_thash_load_v6_addr()
> + * ports/sctp_tag have to be CPU byte order
> + */
> +struct rte_ipv6_tuple {
> +	uint8_t		src_addr[16];
> +	uint8_t		dst_addr[16];
> +	union {
> +		struct {
> +			uint16_t dport;
> +			uint16_t sport;
> +		};
> +		uint32_t        sctp_tag;
> +	};
> +};
> +
> +union rte_thash_tuple {
> +	struct rte_ipv4_tuple	v4;
> +	struct rte_ipv6_tuple	v6;
> +} __aligned(size);
> +
This throws an error on compilation [with unit test patch also applied].

In file included from /home/bruce/dpdk.org/app/test/test_thash.c:40:0:
/home/bruce/dpdk.org/x86_64-native-linuxapp-gcc/include/rte_thash.h:106:1: error: parameter names (without types) in function declaration [-Werror]
 } __aligned(size);
  ^

> +/**
> + * Prepare special converted key to use with rte_softrss_be()
> + * @param orig
> + *   pointer to original RSS key
> + * @param targ
> + *   pointer to target RSS key
> + * @param len
> + *   RSS key length
> + */
> +static inline void
> +rte_convert_rss_key(const uint32_t *orig, uint32_t *targ, int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < (len >> 2); i++)
> +		targ[i] = rte_be_to_cpu_32(orig[i]);
> +}
> +
> +/**
> + * Prepare and load IPv6 address
> + * @param orig
> + *   Pointer to ipv6 header of the original packet
> + * @param targ
> + *   Pointer to rte_ipv6_tuple structure
> + */
> +static inline void
> +rte_thash_load_v6_addr(const struct ipv6_hdr *orig, union rte_thash_tuple *targ)
> +{
> +	__m128i ipv6 = _mm_loadu_si128((const __m128i *)orig->src_addr);
> +	*(__m128i *)targ->v6.src_addr =
> +			_mm_shuffle_epi8(ipv6, rte_thash_ipv6_bswap_mask);
> +	ipv6 = _mm_loadu_si128((const __m128i *)orig->dst_addr);
> +	*(__m128i *)targ->v6.dst_addr =
> +			_mm_shuffle_epi8(ipv6, rte_thash_ipv6_bswap_mask);
> +}

I think the function name needs to be pluralized, and the comment updated to make
it clear that it is not just one IPv6 address that is loaded, but rather both
source and destination.

Regards,
/Bruce