Re: [PATCH v5 02/40] ethdev: support setting and querying RSS algorithm

[fengchengwen <fengchengwen@huawei.com>]

On 2023/10/12 1:39, Stephen Hemminger wrote:
> On Wed, 11 Oct 2023 17:27:27 +0800
> Jie Hai <haijie1@huawei.com> wrote:
> 
>> Currently, rte_eth_rss_conf supports configuring and querying
>> RSS hash functions, rss key and it's length, but not RSS hash
>> algorithm.
>>
>> The structure ``rte_eth_rss_conf`` is extended by adding a new
>> field "algorithm". This represents the RSS algorithms to apply.
>> The following API will be affected:
>> 	- rte_eth_dev_configure
>> 	- rte_eth_dev_rss_hash_update
>> 	- rte_eth_dev_rss_hash_conf_get
>>
>> If the value of "algorithm" used for configuration is a gibberish
>> value, report the error and return. Do the same for
>> rte_eth_dev_rss_hash_update and rte_eth_dev_configure.
>>
>> To check whether the drivers report valid "algorithm", it is set
>> to default value before querying.
>>
>> Signed-off-by: Jie Hai <haijie1@huawei.com>
>> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
>> ---
>>  doc/guides/rel_notes/release_23_11.rst |  2 ++
>>  lib/ethdev/rte_ethdev.c                | 17 ++++++++++++++++
>>  lib/ethdev/rte_ethdev.h                | 27 +++++++++++++++++++++++++
>>  lib/ethdev/rte_flow.c                  |  1 -
>>  lib/ethdev/rte_flow.h                  | 28 ++------------------------
>>  5 files changed, 48 insertions(+), 27 deletions(-)
>>
>> diff --git a/doc/guides/rel_notes/release_23_11.rst b/doc/guides/rel_notes/release_23_11.rst
>> index e13d57728071..92a445ab2ed3 100644
>> --- a/doc/guides/rel_notes/release_23_11.rst
>> +++ b/doc/guides/rel_notes/release_23_11.rst
>> @@ -197,6 +197,8 @@ ABI Changes
>>    fields, to move ``rxq`` and ``txq`` fields, to change the size of
>>    ``reserved1`` and ``reserved2`` fields.
>>  
>> +* ethdev: Added "algorithm" field to ``rte_eth_rss_conf`` structure for RSS
>> +  hash algorithm.
>>  
>>  Known Issues
>>  ------------
>> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>> index 18a4b950b184..2eda1b8072e5 100644
>> --- a/lib/ethdev/rte_ethdev.c
>> +++ b/lib/ethdev/rte_ethdev.c
>> @@ -1464,6 +1464,14 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
>>  		goto rollback;
>>  	}
>>  
>> +	if (dev_conf->rx_adv_conf.rss_conf.algorithm >= RTE_ETH_HASH_FUNCTION_MAX) {
>> +		RTE_ETHDEV_LOG(ERR,
>> +			"Ethdev port_id=%u invalid RSS algorithm: 0x%"PRIx64"\n",
>> +			port_id, dev_conf->rx_adv_conf.rss_conf.algorithm);
>> +		ret = -EINVAL;
>> +		goto rollback;
>> +	}
>> +
> 
> Rather than having every driver check the algorithm, why not handle this like
> other features in DPDK (which may mean API/ABI changes). 
> 
> Add a field rss_algo_capa which is bit field of available RSS functions.
> Then the check for algorithm can be done in generic code. There a couple
> of reserved fields that could be used.

+1 for add a field

But there are two ways to config rss: ethdev-ops, ethdev-rteflow-ops, should distinguish them ? or just define for ethdev-ops ?

> 
> It would mean updating all the drivers once with the capa field but
> would provide way for application to know what fields are possible.
> 
> It has proved to be a problem in later ABI changes if a maximum value
> is exposed. I.e don't expose RTE_ETH_HASH_FUNCTION_MAX.

+1

> 
> .
>