[dpdk-dev] [PATCH v8 4/4] net/ixgbe: use WC store to update queue tail registers

From: Radu Nicolau <radu.nicolau@intel.com>
To: dev@dpdk.org
Cc: beilei.xing@intel.com, jia.guo@intel.com,
	bruce.richardson@intel.com, konstantin.ananyev@intel.com,
	jerinjacobk@gmail.com, david.marchand@redhat.com,
	fiona.trahe@intel.com, wei.zhao1@intel.com, ruifeng.wang@arm.com,
	Radu Nicolau <radu.nicolau@intel.com>
Subject: [dpdk-dev] [PATCH v8 4/4] net/ixgbe: use WC store to update queue tail registers
Date: Fri, 17 Jul 2020 11:49:45 +0100	[thread overview]
Message-ID: <1594982985-31551-5-git-send-email-radu.nicolau@intel.com> (raw)
In-Reply-To: <1594982985-31551-1-git-send-email-radu.nicolau@intel.com>

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/ixgbe/base/ixgbe_osdep.h   |  6 ++++++
 drivers/net/ixgbe/ixgbe_rxtx.c         | 12 ++++++------
 drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c |  4 ++--
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ixgbe/base/ixgbe_osdep.h b/drivers/net/ixgbe/base/ixgbe_osdep.h
index dc712b7..cacf724 100644
--- a/drivers/net/ixgbe/base/ixgbe_osdep.h
+++ b/drivers/net/ixgbe/base/ixgbe_osdep.h
@@ -105,6 +105,12 @@ static inline uint32_t ixgbe_read_addr(volatile void* addr)
 #define IXGBE_PCI_REG_WRITE_RELAXED(reg, value)		\
 	rte_write32_relaxed((rte_cpu_to_le_32(value)), reg)
 
+#define IXGBE_PCI_REG_WC_WRITE(reg, value)			\
+	rte_write32_wc((rte_cpu_to_le_32(value)), reg)
+
+#define IXGBE_PCI_REG_WC_WRITE_RELAXED(reg, value)		\
+	rte_write32_wc_relaxed((rte_cpu_to_le_32(value)), reg)
+
 #define IXGBE_PCI_REG_ADDR(hw, reg) \
 	((volatile uint32_t *)((char *)(hw)->hw_addr + (reg)))
 
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index 2e20e18..669b23e 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -308,7 +308,7 @@ tx_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 
 	/* update tail pointer */
 	rte_wmb();
-	IXGBE_PCI_REG_WRITE_RELAXED(txq->tdt_reg_addr, txq->tx_tail);
+	IXGBE_PCI_REG_WC_WRITE_RELAXED(txq->tdt_reg_addr, txq->tx_tail);
 
 	return nb_pkts;
 }
@@ -946,7 +946,7 @@ ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	PMD_TX_LOG(DEBUG, "port_id=%u queue_id=%u tx_tail=%u nb_tx=%u",
 		   (unsigned) txq->port_id, (unsigned) txq->queue_id,
 		   (unsigned) tx_id, (unsigned) nb_tx);
-	IXGBE_PCI_REG_WRITE_RELAXED(txq->tdt_reg_addr, tx_id);
+	IXGBE_PCI_REG_WC_WRITE_RELAXED(txq->tdt_reg_addr, tx_id);
 	txq->tx_tail = tx_id;
 
 	return nb_tx;
@@ -1692,7 +1692,7 @@ rx_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 
 		/* update tail pointer */
 		rte_wmb();
-		IXGBE_PCI_REG_WRITE_RELAXED(rxq->rdt_reg_addr,
+		IXGBE_PCI_REG_WC_WRITE_RELAXED(rxq->rdt_reg_addr,
 					    cur_free_trigger);
 	}
 
@@ -1918,7 +1918,7 @@ ixgbe_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 			   (unsigned) nb_rx);
 		rx_id = (uint16_t) ((rx_id == 0) ?
 				     (rxq->nb_rx_desc - 1) : (rx_id - 1));
-		IXGBE_PCI_REG_WRITE(rxq->rdt_reg_addr, rx_id);
+		IXGBE_PCI_REG_WC_WRITE(rxq->rdt_reg_addr, rx_id);
 		nb_hold = 0;
 	}
 	rxq->nb_rx_hold = nb_hold;
@@ -2096,7 +2096,7 @@ ixgbe_recv_pkts_lro(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts,
 
 			if (!ixgbe_rx_alloc_bufs(rxq, false)) {
 				rte_wmb();
-				IXGBE_PCI_REG_WRITE_RELAXED(rxq->rdt_reg_addr,
+				IXGBE_PCI_REG_WC_WRITE_RELAXED(rxq->rdt_reg_addr,
 							    next_rdt);
 				nb_hold -= rxq->rx_free_thresh;
 			} else {
@@ -2262,7 +2262,7 @@ ixgbe_recv_pkts_lro(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts,
 			   rxq->port_id, rxq->queue_id, rx_id, nb_hold, nb_rx);
 
 		rte_wmb();
-		IXGBE_PCI_REG_WRITE_RELAXED(rxq->rdt_reg_addr, prev_id);
+		IXGBE_PCI_REG_WC_WRITE_RELAXED(rxq->rdt_reg_addr, prev_id);
 		nb_hold = 0;
 	}
 
diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
index 517ca31..e77a7f3 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
@@ -90,7 +90,7 @@ ixgbe_rxq_rearm(struct ixgbe_rx_queue *rxq)
 			     (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
 
 	/* Update the tail pointer on the NIC */
-	IXGBE_PCI_REG_WRITE(rxq->rdt_reg_addr, rx_id);
+	IXGBE_PCI_REG_WC_WRITE(rxq->rdt_reg_addr, rx_id);
 }
 
 #ifdef RTE_LIBRTE_SECURITY
@@ -697,7 +697,7 @@ ixgbe_xmit_fixed_burst_vec(void *tx_queue, struct rte_mbuf **tx_pkts,
 
 	txq->tx_tail = tx_id;
 
-	IXGBE_PCI_REG_WRITE(txq->tdt_reg_addr, txq->tx_tail);
+	IXGBE_PCI_REG_WC_WRITE(txq->tdt_reg_addr, txq->tx_tail);
 
 	return nb_pkts;
 }
-- 
2.7.4

