> -----Original Message-----
> From: Zhang, Qi Z <[email protected]>
> Sent: Thursday, April 27, 2023 3:38 PM
> To: Feifei Wang <[email protected]>; Richardson, Bruce
> <[email protected]>; Konstantin Ananyev
> <[email protected]>; Zhang, Yuying
> <[email protected]>; Xing, Beilei <[email protected]>; David
> Christensen <[email protected]>; Ruifeng Wang
> <[email protected]>
> Cc: [email protected]; [email protected]; Honnappa Nagarahalli
> <[email protected]>
> Subject: RE: [PATCH v2] net/i40e: remove redundant judgment
>
>
>
> > -----Original Message-----
> > From: Feifei Wang <[email protected]>
> > Sent: Tuesday, March 28, 2023 3:28 PM
> > To: Richardson, Bruce <[email protected]>; Konstantin Ananyev
> > <[email protected]>; Zhang, Yuying
> > <[email protected]>; Xing, Beilei <[email protected]>; David
> > Christensen <[email protected]>; Ruifeng Wang
> > <[email protected]>
> > Cc: [email protected]; [email protected]; Feifei Wang <[email protected]>;
> > Honnappa Nagarahalli <[email protected]>
> > 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?
Ping
>
> Otherwise
> Acked-by: Qi Zhang <[email protected]>
>
>
> >
> >
> > v2:
> > 1. add change for avx and altivec path.
> >
> > Suggested-by: Honnappa Nagarahalli <[email protected]>
> > Signed-off-by: Feifei Wang <[email protected]>
> > Reviewed-by: Ruifeng Wang <[email protected]>
> > ---
> > 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
