On 11/1/2023 7:40 AM, Jie Hai wrote:
> 1. overwrite the comments of fields of 'rte_eth_rss_conf'.
> 2. Add comments for RTE_ETH_HASH_FUNCTION_DEFAULT.
>
> Signed-off-by: Jie Hai <haij...@huawei.com>
> ---
> lib/ethdev/rte_ethdev.h | 34 +++++++++++++++++++---------------
> lib/ethdev/rte_flow.h | 1 +
> 2 files changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index a53dd5a1efec..343a134fdd12 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -448,24 +448,28 @@ struct rte_vlan_filter_conf {
> /**
> * A structure used to configure the Receive Side Scaling (RSS) feature
> * of an Ethernet port.
> - * If not NULL, the *rss_key* pointer of the *rss_conf* structure points
> - * to an array holding the RSS key to use for hashing specific header
> - * fields of received packets. The length of this array should be indicated
> - * by *rss_key_len* below. Otherwise, a default random hash key is used by
> - * the device driver.
> - *
> - * The *rss_key_len* field of the *rss_conf* structure indicates the length
> - * in bytes of the array pointed by *rss_key*. To be compatible, this length
> - * will be checked in i40e only. Others assume 40 bytes to be used as before.
> - *
> - * The *rss_hf* field of the *rss_conf* structure indicates the different
> - * types of IPv4/IPv6 packets to which the RSS hashing must be applied.
> - * Supplying an *rss_hf* equal to zero disables the RSS feature.
> */
> struct rte_eth_rss_conf {
> - uint8_t *rss_key; /**< If not NULL, 40-byte hash key. */
> + /**
> + * In rte_eth_dev_rss_hash_conf_get(), the *rss_key_len* should be
> + * greater than or equal to the *hash_key_size* which get from
> + * rte_eth_dev_info_get() API. And the *rss_key* should contain at least
> + * *hash_key_size* bytes. If not meet these requirements, the query
> + * result is unreliable even if the operation returns success.
> + *
> + * In rte_eth_dev_rss_hash_update() or rte_eth_dev_configure(), if
> + * *rss_key* is not NULL, the *rss_key_len* indicates the length of the
> + * *rss_key* in bytes of the array pointed by *rss_key*,
>
I think it is sufficient to say "length of the *rss_key* in bytes".
> and it should
> + * be equal to *hash_key_size*.
>
I don't know if we missed something here, first driver reports key size
via 'rte_eth_dev_info_get()::hash_key_size', later other APIs require
'rss_key_len' parameter that should be same as 'hash_key_size', as
driver already know this parameter why we are requesting it back from
the application?
>> Otherwise, drivers are free to use a
> + * random or a default key or to ignore this configuration.
> + */
>
I guess above clause describes when 'rss_key' is null, can you please
clarify it as following, perhaps with a line break:
"If *rss_key* is NULL, drivers are free to use a random or a default key."
For the "Drivers are free to ignore the *rss_key_len* and assume key
length is 40 bytes." part, as checks in ethdev layer now forces
application to provide 'rss_key_len' as 'hash_key_size', I think we can
remove above, as application will provide 40 bytes when it is the case.
My concern is this check now can break some applications, because
'rss_key_len' wasn't mandatory previously, but it became now.
Overall it becomes:
"
In rte_eth_dev_rss_hash_update() or rte_eth_dev_configure(), if
*rss_key* is not NULL, the *rss_key_len* indicates the length of the
*rss_key* in bytes and it should be equal to *hash_key_size*.
If *rss_key* is NULL, drivers are free to use a random or a default key.
"
> + uint8_t *rss_key;
> uint8_t rss_key_len; /**< hash key length in bytes. */
> - uint64_t rss_hf; /**< Hash functions to apply - see below. */
> + /**
> + * Indicates the type of packets or the specific part of packets to
> + * which RSS hashing is to be applied.
> + */
> + uint64_t rss_hf;
> };
>
> /*
> diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h
> index c16fe8c21f2f..751c29a0f3f3 100644
> --- a/lib/ethdev/rte_flow.h
> +++ b/lib/ethdev/rte_flow.h
> @@ -3226,6 +3226,7 @@ struct rte_flow_query_count {
> * Hash function types.
> */
> enum rte_eth_hash_function {
> + /** DEFAULT means driver decides which hash algorithm to pick. */
> RTE_ETH_HASH_FUNCTION_DEFAULT = 0,
> RTE_ETH_HASH_FUNCTION_TOEPLITZ, /**< Toeplitz */
> RTE_ETH_HASH_FUNCTION_SIMPLE_XOR, /**< Simple XOR */
