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

[David Marchand]

On Wed, Apr 28, 2021 at 9:21 AM Min Hu (Connor) <humin29 at huawei.com> wrote:
>
> From: Chengchang Tang <tangchengchang at 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 at dpdk.org
>
> Signed-off-by: Chengchang Tang <tangchengchang at huawei.com>
> Signed-off-by: Min Hu (Connor) <humin29 at 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


-- 
David Marchand