[dpdk-dev] [PATCH] net/ice: use write combining store for tail updates on AVX512 path.

[dpdk-dev] [PATCH] net/ice: use write combining store for tail updates on AVX512 path.

[Radu Nicolau]

Performance improvement: use a write combining store
instead of a regular mmio write to update queue tail
registers.

Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
---
 drivers/net/ice/ice_rxtx_vec_avx512.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ice/ice_rxtx_vec_avx512.c b/drivers/net/ice/ice_rxtx_vec_avx512.c
index 0e5a676e6..9f3501238 100644
--- a/drivers/net/ice/ice_rxtx_vec_avx512.c
+++ b/drivers/net/ice/ice_rxtx_vec_avx512.c
@@ -125,7 +125,7 @@ ice_rxq_rearm(struct ice_rx_queue *rxq)
 			     (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
 
 	/* Update the tail pointer on the NIC */
-	ICE_PCI_REG_WRITE(rxq->qrx_tail, rx_id);
+	ICE_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id);
 }
 
 static inline __m256i
@@ -1111,7 +1111,7 @@ ice_xmit_fixed_burst_vec_avx512(void *tx_queue, struct rte_mbuf **tx_pkts,
 
 	txq->tx_tail = tx_id;
 
-	ICE_PCI_REG_WRITE(txq->qtx_tail, txq->tx_tail);
+	ICE_PCI_REG_WC_WRITE(txq->qtx_tail, txq->tx_tail);
 
 	return nb_pkts;
 }
-- 
2.17.1

Re: [dpdk-dev] [PATCH] net/ice: use write combining store for tail updates on AVX512 path.

[Zhang, Qi Z]

> -----Original Message-----
> From: Nicolau, Radu <radu.nicolau@intel.com>
> Sent: Friday, April 9, 2021 6:09 PM
> To: dev@dpdk.org
> Cc: Richardson, Bruce <bruce.richardson@intel.com>; Rong, Leyi
> <leyi.rong@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>; Lu, Wenzhuo
> <wenzhuo.lu@intel.com>; Nicolau, Radu <radu.nicolau@intel.com>
> Subject: [PATCH] net/ice: use write combining store for tail updates on
> AVX512 path.
> 
> Performance improvement: use a write combining store instead of a regular
> mmio write to update queue tail registers.
> 
> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>

Acked-by: Qi Zhang <qi.z.zhang@intel.com>

Applied to dpdk-next-net-intel.

Thanks
Qi