> -----Original Message-----
> From: Feifei Wang <feifei.wa...@arm.com>
> Sent: Tuesday, March 28, 2023 3:28 PM
> To: Richardson, Bruce <bruce.richard...@intel.com>; Konstantin Ananyev
> <konstantin.v.anan...@yandex.ru>; Zhang, Yuying
> <yuying.zh...@intel.com>; Xing, Beilei <beilei.x...@intel.com>; David
> Christensen <d...@linux.vnet.ibm.com>; Ruifeng Wang
> <ruifeng.w...@arm.com>
> Cc: dev@dpdk.org; n...@arm.com; Feifei Wang <feifei.wa...@arm.com>;
> Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
> Subject: [PATCH v2] net/i40e: remove redundant judgment
>
> Merged variable updates under the same condition. It reduces branch.
>
> In ampere-altra, there is no performance improvement with this patch.
> In x86 sse and avx2 path, there is also no performance improvement.
Thanks for sharing the results. While the code implements some best practices,
such as reducing branching and adding compiler hints, which should generally
improve performance, it's not necessary to highlight that it didn't provide
benefits on certain specific platforms.
Would it be ok to remove the last two lines when merging the patch?
Otherwise
Acked-by: Qi Zhang <qi.z.zh...@intel.com>
>
>
> v2:
> 1. add change for avx and altivec path.
>
> Suggested-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
> Signed-off-by: Feifei Wang <feifei.wa...@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
> ---
> drivers/net/i40e/i40e_rxtx_common_avx.h | 9 +++++----
> drivers/net/i40e/i40e_rxtx_vec_altivec.c | 9 +++++----
> drivers/net/i40e/i40e_rxtx_vec_neon.c | 9 +++++----
> drivers/net/i40e/i40e_rxtx_vec_sse.c | 9 +++++----
> 4 files changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/i40e/i40e_rxtx_common_avx.h
> b/drivers/net/i40e/i40e_rxtx_common_avx.h
> index cfc1e63173..85958d6c81 100644
> --- a/drivers/net/i40e/i40e_rxtx_common_avx.h
> +++ b/drivers/net/i40e/i40e_rxtx_common_avx.h
> @@ -198,14 +198,15 @@ i40e_rxq_rearm_common(struct i40e_rx_queue
> *rxq, __rte_unused bool avx512) #endif
>
> rxq->rxrearm_start += RTE_I40E_RXQ_REARM_THRESH;
> - if (rxq->rxrearm_start >= rxq->nb_rx_desc)
> + rx_id = rxq->rxrearm_start - 1;
> +
> + if (unlikely(rxq->rxrearm_start >= rxq->nb_rx_desc)) {
> rxq->rxrearm_start = 0;
> + rx_id = rxq->nb_rx_desc - 1;
> + }
>
> rxq->rxrearm_nb -= RTE_I40E_RXQ_REARM_THRESH;
>
> - rx_id = (uint16_t)((rxq->rxrearm_start == 0) ?
> - (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
> -
> /* Update the tail pointer on the NIC */
> I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id); } diff --git
> a/drivers/net/i40e/i40e_rxtx_vec_altivec.c
> b/drivers/net/i40e/i40e_rxtx_vec_altivec.c
> index 2dfa04599c..8672ad1c41 100644
> --- a/drivers/net/i40e/i40e_rxtx_vec_altivec.c
> +++ b/drivers/net/i40e/i40e_rxtx_vec_altivec.c
> @@ -89,14 +89,15 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
> }
>
> rxq->rxrearm_start += RTE_I40E_RXQ_REARM_THRESH;
> - if (rxq->rxrearm_start >= rxq->nb_rx_desc)
> + rx_id = rxq->rxrearm_start - 1;
> +
> + if (unlikely(rxq->rxrearm_start >= rxq->nb_rx_desc)) {
> rxq->rxrearm_start = 0;
> + rx_id = rxq->nb_rx_desc - 1;
> + }
>
> rxq->rxrearm_nb -= RTE_I40E_RXQ_REARM_THRESH;
>
> - rx_id = (uint16_t)((rxq->rxrearm_start == 0) ?
> - (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
> -
> /* Update the tail pointer on the NIC */
> I40E_PCI_REG_WRITE(rxq->qrx_tail, rx_id); } diff --git
> a/drivers/net/i40e/i40e_rxtx_vec_neon.c
> b/drivers/net/i40e/i40e_rxtx_vec_neon.c
> index 12e6f1cbcb..49391fe4c7 100644
> --- a/drivers/net/i40e/i40e_rxtx_vec_neon.c
> +++ b/drivers/net/i40e/i40e_rxtx_vec_neon.c
> @@ -64,14 +64,15 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
> }
>
> rxq->rxrearm_start += RTE_I40E_RXQ_REARM_THRESH;
> - if (rxq->rxrearm_start >= rxq->nb_rx_desc)
> + rx_id = rxq->rxrearm_start - 1;
> +
> + if (unlikely(rxq->rxrearm_start >= rxq->nb_rx_desc)) {
> rxq->rxrearm_start = 0;
> + rx_id = rxq->nb_rx_desc - 1;
> + }
>
> rxq->rxrearm_nb -= RTE_I40E_RXQ_REARM_THRESH;
>
> - rx_id = (uint16_t)((rxq->rxrearm_start == 0) ?
> - (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
> -
> rte_io_wmb();
> /* Update the tail pointer on the NIC */
> I40E_PCI_REG_WRITE_RELAXED(rxq->qrx_tail, rx_id); diff --git
> a/drivers/net/i40e/i40e_rxtx_vec_sse.c
> b/drivers/net/i40e/i40e_rxtx_vec_sse.c
> index bdc979a839..baf83cb3df 100644
> --- a/drivers/net/i40e/i40e_rxtx_vec_sse.c
> +++ b/drivers/net/i40e/i40e_rxtx_vec_sse.c
> @@ -77,14 +77,15 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
> }
>
> rxq->rxrearm_start += RTE_I40E_RXQ_REARM_THRESH;
> - if (rxq->rxrearm_start >= rxq->nb_rx_desc)
> + rx_id = rxq->rxrearm_start - 1;
> +
> + if (unlikely(rxq->rxrearm_start >= rxq->nb_rx_desc)) {
> rxq->rxrearm_start = 0;
> + rx_id = rxq->nb_rx_desc - 1;
> + }
>
> rxq->rxrearm_nb -= RTE_I40E_RXQ_REARM_THRESH;
>
> - rx_id = (uint16_t)((rxq->rxrearm_start == 0) ?
> - (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
> -
> /* Update the tail pointer on the NIC */
> I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id); }
> --
> 2.25.1
