Re: [PATCH v3 1/4] ethdev: introduce ethdev HW desc dump PI

[Dongdong Liu <liudongdong3@huawei.com>]

Hi Andrew

Many thanks for your review.

On 2022/6/8 18:09, Andrew Rybchenko wrote:
> Cc various driver maintainers looking for opinion about API discussion
> below
>
> On 6/7/22 16:59, Dongdong Liu wrote:
>> Hi Andrew
>>
>> Many thanks for your review.
>>
>> On 2022/6/2 3:53, Andrew Rybchenko wrote:
>>> On 6/1/22 10:49, Min Hu (Connor) wrote:
>>>> Added the ethdev HW Rx desc dump API which provides functions for query
>>>> HW descriptor from device. HW descriptor info differs in different
>>>> NICs.
>>>> The information demonstrates I/O process which is important for debug.
>>>> As the information is different between NICs, the new API is
>>>> introduced.
>>>>
>>>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
>>>> ---
>>>>   doc/guides/rel_notes/release_22_07.rst |  7 ++++
>>>>   lib/ethdev/ethdev_driver.h             | 42 ++++++++++++++++++++++++
>>>>   lib/ethdev/rte_ethdev.c                | 44
>>>> ++++++++++++++++++++++++++
>>>>   lib/ethdev/rte_ethdev.h                | 44
>>>> ++++++++++++++++++++++++++
>>>>   lib/ethdev/version.map                 |  2 ++
>>>>   5 files changed, 139 insertions(+)
>>>>
>>>> diff --git a/doc/guides/rel_notes/release_22_07.rst
>>>> b/doc/guides/rel_notes/release_22_07.rst
>>>> index 8932a1d478..56c675121a 100644
>>>> --- a/doc/guides/rel_notes/release_22_07.rst
>>>> +++ b/doc/guides/rel_notes/release_22_07.rst
>>>> @@ -137,6 +137,13 @@ New Features
>>>>     * ``RTE_EVENT_QUEUE_ATTR_WEIGHT``
>>>>     * ``RTE_EVENT_QUEUE_ATTR_AFFINITY``
>>>>   +* **Added ethdev HW desc dump API, to dump Rx/Tx HW desc info from
>>>> device.**
>>>> +
>>>> +  Added the ethdev HW Rx desc dump API which provides functions for
>>>> query
>>>> +  HW descriptor from device. HW descriptor info differs in different
>>>> NICs.
>>>> +  The information demonstrates I/O process which is important for
>>>> debug.
>>>> +  As the information is different between NICs, the new API is
>>>> introduced.
>>>> +
>>>>     Removed Items
>>>>   -------------
>>>> diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
>>>> index 69d9dc21d8..9c1726eb2d 100644
>>>> --- a/lib/ethdev/ethdev_driver.h
>>>> +++ b/lib/ethdev/ethdev_driver.h
>>>> @@ -1073,6 +1073,42 @@ typedef int
>>>> (*eth_ip_reassembly_conf_set_t)(struct rte_eth_dev *dev,
>>>>    */
>>>>   typedef int (*eth_dev_priv_dump_t)(struct rte_eth_dev *dev, FILE
>>>> *file);
>>>>   +/**
>>>> + * @internal
>>>> + * Dump ethdev Rx descriptor info to a file.
>>>
>>> ethdev is not required in the description above. It is an ethdev
>>> operation type.
>>
>> Will remove it.
>>>
>>> Is there any limitations on caller context? Should be it the same
>>> CPU core (since typically it is the case for per-queue API) which
>>> polls the queue? The answer must be in the API function description.
>>
>> "[PATCH v3 4/4] app/procinfo: support descriptor dump" shows how to use
>> the API. It is used for debug, not a dataplane API,  no special
>> limitations on caller context.
>
> Please, be explicit in the ethdev API documentation.
OK, will do
>
>>>
>>>> + *
>>>> + * @param file
>>>> + *   A pointer to a file for output.
>>>> + * @param dev
>>>> + *   Port (ethdev) handle.
>>>> + * @param queue_id
>>>> + *   The selected queue.
>>>> + * @param desc_id
>>>> + *   The selected descriptor.
>>>
>>> Is it an ID in the ring regardless of the current position or
>>> is it offset relative to current position in the ring?
>>> It should be clarified in any case.
>>> I'd say that it should be an offset to be consistent with
>>> descriptor status API.
>>
>> It is an ID in the ring regardless of the current position.
>
> IMHO, it is inconvenient since typically it is interesting
> what happens nearby current position.
>
OK, will fix.
>>>
>>> It would be useful to be able to dump many descriptor at once.
>> This can be done by the appliacation.
>
> Yes, that's true, but easy to do in the driver as well. It would
> be especially important if ID semantics changes.
How about changing parameter 'desc_id' to 'num' to dump
[current position, current position + num - 1] descriptors.

/**
  * @internal
  * Dump Rx descriptor info to a file.
  *
  * @param file
  *   A pointer to a file for output.
  * @param dev
  *   Port (ethdev) handle.
  * @param queue_id
  *   The selected queue.
  * @param num
  *   The number of the descriptors to dump.
  * @return
  *   Negative errno value on error, zero on success. 
 

  */
typedef int (*eth_rx_hw_desc_dump_t)(FILE *file, const struct 
rte_eth_dev *dev,
									 uint16_t queue_id, uint16_t num);
>
>>>
>>>> + * @return
>>>> + *   Negative errno value on error, zero on success.
>>>> + */
>>>> +typedef int (*eth_rx_hw_desc_dump_t)(FILE *file, const struct
>>>> rte_eth_dev *dev,
>>>> +                     uint16_t queue_id, uint16_t desc_id);
>>>> +
>>>> +/**
>>>> + * @internal
>>>> + * Dump ethdev Tx descriptor info to a file.
>>>> + *
>>>> + * @param file
>>>> + *   A pointer to a file for output.
>>>> + * @param dev
>>>> + *   Port (ethdev) handle.
>>>> + * @param queue_id
>>>> + *   The selected queue.
>>>> + * @param desc_id
>>>> + *   The selected descriptor.
>>>> + * @return
>>>> + *   Negative errno value on error, zero on success.
>>>> + */
>>>> +typedef int (*eth_tx_hw_desc_dump_t)(FILE *file, const struct
>>>> rte_eth_dev *dev,
>>>> +                     uint16_t queue_id, uint16_t desc_id);
>>>> +
>>>>   /**
>>>>    * @internal A structure containing the functions exported by an
>>>> Ethernet driver.
>>>>    */
>>>> @@ -1283,6 +1319,12 @@ struct eth_dev_ops {
>>>>         /** Dump private info from device */
>>>>       eth_dev_priv_dump_t eth_dev_priv_dump;
>>>> +
>>>> +    /** Dump ethdev Rx descriptor info */\\
>>>
>>> It is an ethdev operations. So, 'ethdev' is not necessary in the
>>> description.
>> Will fix.
>>>
>>>> +    eth_rx_hw_desc_dump_t eth_rx_hw_desc_dump;
>>>> +
>>>> +    /** Dump ethdev Tx descriptor info */
>>>> +    eth_tx_hw_desc_dump_t eth_tx_hw_desc_dump;
>>>>   };
>>>>     /**
>>>> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>>>> index 46c088dc88..bbd8439fa0 100644
>>>> --- a/lib/ethdev/rte_ethdev.c
>>>> +++ b/lib/ethdev/rte_ethdev.c
>>>> @@ -5876,6 +5876,50 @@ rte_eth_dev_priv_dump(uint16_t port_id, FILE
>>>> *file)
>>>>       return eth_err(port_id, (*dev->dev_ops->eth_dev_priv_dump)(dev,
>>>> file));
>>>>   }
>>>>   +int
>>>> +rte_eth_rx_hw_desc_dump(FILE *file, uint16_t port_id, uint16_t
>>>> queue_id,
>>>> +            uint16_t desc_id)
>>>> +{
>>>> +    struct rte_eth_dev *dev;
>>>> +    int ret;
>>>> +
>>>> +    RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>>>> +    dev = &rte_eth_devices[port_id];
>>>
>>> Shouldn't we check file vs null?
>> Yes, will do.
>>>
>>>> +
>>>> +    if (queue_id >= dev->data->nb_rx_queues) {
>>>> +        RTE_ETHDEV_LOG(ERR, "Invalid Rx queue_id=%u\n", queue_id);
>>>> +        return -EINVAL;
>>>> +    }
>>>
>>> Don't we need a check vs queue size?
>>
>> This need to be done in pmd as "[PATCH v3 3/4] net/hns3: support Rx/Tx
>> bd dump" shows.
>
> All applicable generic checks must be done on ethdev level to avoid code
> duplication and missing checks in PMDs.
The ethdev level does not know the queue size.
This is similar to rte_eth_rx_descriptor_status(),
queue size check is also done in PMDs.

Thanks,
Dongdong.
>
> Andrew.
> .
>