Re: [dpdk-dev] [PATCH V2] ethdev: add queue state when retrieve queue information

[Ferruh Yigit <ferruh.yigit@intel.com>]

Hi Lijun,

Let's try to complete this for the release.

On 4/6/2021 3:02 PM, Ananyev, Konstantin wrote:
> Hi,
> 
>> Currently, upper-layer application could get queue state only
>> through pointers such as dev->data->tx_queue_state[queue_id],
>> this is not the recommended way to access it. So this patch
>> add get queue state when call rte_eth_rx_queue_info_get and
>> rte_eth_tx_queue_info_get API.
>>
>> Note: The hairpin queue is not supported with above
>> rte_eth_*x_queue_info_get, so the queue state could be
>> RTE_ETH_QUEUE_STATE_STARTED or RTE_ETH_QUEUE_STATE_STOPPED.
> 
> I wonder why RTE_ETH_QUEUE_STATE_HAIRPIN Is not supported?
> Obviously what we do - copy internal queue state to the user provided buffer.
> 

+1, with current implementation we can't say it is only for start & stop.

Since 'STATE_HAIRPIN' is all internal, it may be possible to separate it into 
its own variable and expose only start and stop, but I don't think it worth the 
effort, why not just expose all possible states.


>> Note: After add queue_state field, the 'struct rte_eth_rxq_info' size
>> remains 128B, and the 'struct rte_eth_txq_info' size remains 64B, so
>> it could be ABI compatible.
>>
>> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
>> ---
>> V1->V2:
>> - move queue state defines to public file
>> ---
>>   doc/guides/rel_notes/release_21_05.rst |  6 ++++++
>>   lib/librte_ethdev/ethdev_driver.h      |  7 -------
>>   lib/librte_ethdev/rte_ethdev.c         |  3 +++
>>   lib/librte_ethdev/rte_ethdev.h         | 11 +++++++++++
>>   4 files changed, 20 insertions(+), 7 deletions(-)
>>
>> diff --git a/doc/guides/rel_notes/release_21_05.rst b/doc/guides/rel_notes/release_21_05.rst
>> index 22aa80a..503daf9 100644
>> --- a/doc/guides/rel_notes/release_21_05.rst
>> +++ b/doc/guides/rel_notes/release_21_05.rst
>> @@ -164,6 +164,12 @@ ABI Changes
>>
>>   * No ABI change that would break compatibility with 20.11.
>>
>> +* Added new field ``queue_state`` to ``rte_eth_rxq_info`` structure
>> +  to provide indicated rxq queue state.
>> +
>> +* Added new field ``queue_state`` to ``rte_eth_txq_info`` structure
>> +  to provide indicated txq queue state.
>> +
>>
>>   Known Issues
>>   ------------
>> diff --git a/lib/librte_ethdev/ethdev_driver.h b/lib/librte_ethdev/ethdev_driver.h
>> index cdd4b43..ec5a17d 100644
>> --- a/lib/librte_ethdev/ethdev_driver.h
>> +++ b/lib/librte_ethdev/ethdev_driver.h
>> @@ -970,13 +970,6 @@ struct eth_dev_ops {
>>   };
>>
>>   /**
>> - * RX/TX queue states
>> - */
>> -#define RTE_ETH_QUEUE_STATE_STOPPED 0
>> -#define RTE_ETH_QUEUE_STATE_STARTED 1
>> -#define RTE_ETH_QUEUE_STATE_HAIRPIN 2
>> -
>> -/**
>>    * @internal
>>    * Check if the selected Rx queue is hairpin queue.
>>    *
>> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
>> index 3059aa5..fbd10b2 100644
>> --- a/lib/librte_ethdev/rte_ethdev.c
>> +++ b/lib/librte_ethdev/rte_ethdev.c
>> @@ -5042,6 +5042,8 @@ rte_eth_rx_queue_info_get(uint16_t port_id, uint16_t queue_id,
>>
>>   memset(qinfo, 0, sizeof(*qinfo));
>>   dev->dev_ops->rxq_info_get(dev, queue_id, qinfo);
>> +qinfo->queue_state = dev->data->rx_queue_state[queue_id];
>> +
>>   return 0;
>>   }
>>
>> @@ -5082,6 +5084,7 @@ rte_eth_tx_queue_info_get(uint16_t port_id, uint16_t queue_id,
>>
>>   memset(qinfo, 0, sizeof(*qinfo));
>>   dev->dev_ops->txq_info_get(dev, queue_id, qinfo);
>> +qinfo->queue_state = dev->data->tx_queue_state[queue_id];
>>
>>   return 0;
>>   }
>> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
>> index efda313..4f0b1b2 100644
>> --- a/lib/librte_ethdev/rte_ethdev.h
>> +++ b/lib/librte_ethdev/rte_ethdev.h
>> @@ -1582,6 +1582,13 @@ struct rte_eth_dev_info {
>>   };
>>
>>   /**
>> + * RX/TX queue states
>> + */
>> +#define RTE_ETH_QUEUE_STATE_STOPPED 0
>> +#define RTE_ETH_QUEUE_STATE_STARTED 1
>> +#define RTE_ETH_QUEUE_STATE_HAIRPIN 2
>> +
>> +/**
>>    * Ethernet device RX queue information structure.
>>    * Used to retrieve information about configured queue.
>>    */
>> @@ -1591,6 +1598,8 @@ struct rte_eth_rxq_info {
>>   uint8_t scattered_rx;       /**< scattered packets RX supported. */
>>   uint16_t nb_desc;           /**< configured number of RXDs. */
>>   uint16_t rx_buf_size;       /**< hardware receive buffer size. */
>> +/**< Queues state: STARTED(1) / STOPPED(0). */
> 
> I think comment has to state that possible values are one of
> RTE_ETH_QUEUE_STATE_*.
> About previous discussion about new field in this struct vs new API function,
> I still think new function will be a bit cleaner, but could live with both.
> 
>> +uint8_t queue_state;
> 
> If we'll go with new 1B field, then as Stephen pointed,
> it is probably worth to fill the hole between scattered_rx
> and nb_desc with this new filed.
> 

+1

>>   } __rte_cache_min_aligned;
>>
>>   /**
>> @@ -1600,6 +1609,8 @@ struct rte_eth_rxq_info {
>>   struct rte_eth_txq_info {
>>   struct rte_eth_txconf conf; /**< queue config parameters. */
>>   uint16_t nb_desc;           /**< configured number of TXDs. */
>> +/**< Queues state: STARTED(1) / STOPPED(0). */
> 
> Same about comment here.
> 
>> +uint8_t queue_state;
>>   } __rte_cache_min_aligned;
>>
>>   /* Generic Burst mode flag definition, values can be ORed. */
>> --
>> 2.7.4
> 


Other comments I case see:

1- Make QUEUE_STATE enum
   For consistency with existing usage I think we can keep it as it is

2- Make a specific API to get the queue state
   No strong opinion, I think we can go with this one

3- Use enum type in "struct rte_eth_rxq_info"
   Which make sense but we don't have space in current struct, also 
'rte_eth_dev_data' has variable to hold same, and for consistency if we change 
it to enum in it, that is even wider change. I think it doesn't worth the effort 
and we can continue with 'uint8_t'

Please add if any is missing, and if there is any strong opinion on above.


If there is no objection, only required changes are above two issues commented 
inline,
- Remove comment/note that this is only for start/stop states
- Replace the field location to benefit from gap in struct