Re: [dpdk-dev] [PATCH 5/5] net/hns3: select Tx prepare based on Tx offload

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

On 5/7/2021 10:26 AM, David Marchand wrote:
> On Wed, Apr 28, 2021 at 9:21 AM Min Hu (Connor) <humin29@huawei.com> wrote:
>>
>> From: Chengchang Tang <tangchengchang@huawei.com>
>>
>> Tx prepare should be called only when necessary to reduce the impact on
>> performance.
>>
>> For partial TX offload, users need to call rte_eth_tx_prepare() to invoke
>> the tx_prepare callback of PMDs. In this callback, the PMDs adjust the
>> packet based on the offloading used by the user. (e.g. For some PMDs,
>> pseudo-headers need to be calculated when the TX cksum is offloaded.)
>>
>> However, for the users, they cannot grasp all the hardware and PMDs
>> characteristics. As a result, users cannot decide when they need to
>> actually call tx_prepare. Therefore, we should assume that the user calls
>> rte_eth_tx_prepare() when using any Tx offloading to ensure that related
>> functions work properly. Whether packets need to be adjusted should be
>> determined by PMDs. They can make judgments in the dev_configure or
>> queue_setup phase. When the related function is not used, the pointer of
>> tx_prepare should be set to NULL to reduce the performance loss caused by
>> invoking rte_eth_tx_repare().
>>
>> In this patch, if tx_prepare is not required for the offloading used by
>> the users, the tx_prepare pointer will be set to NULL.
>>
>> Fixes: bba636698316 ("net/hns3: support Rx/Tx and related operations")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
>> ---
>>  drivers/net/hns3/hns3_rxtx.c | 36 +++++++++++++++++++++++++++++++++---
>>  1 file changed, 33 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/hns3/hns3_rxtx.c b/drivers/net/hns3/hns3_rxtx.c
>> index 3881a72..7ac3a48 100644
>> --- a/drivers/net/hns3/hns3_rxtx.c
>> +++ b/drivers/net/hns3/hns3_rxtx.c
>> @@ -4203,17 +4203,45 @@ hns3_tx_check_simple_support(struct rte_eth_dev *dev)
>>         return (offloads == (offloads & DEV_TX_OFFLOAD_MBUF_FAST_FREE));
>>  }
>>
>> +static bool
>> +hns3_get_tx_prep_needed(struct rte_eth_dev *dev)
>> +{
>> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
>> +       /* always perform tx_prepare when debug */
>> +       return true;
> 
> dev is unused in this case.
> http://mails.dpdk.org/archives/test-report/2021-May/193391.html
> 

Thanks David,

@Connor, can you please send a quick fix for it?
'RTE_SET_USED(dev);' should fix it.