net/i40e: use write combining store for tail updates

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: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Wenzhuo Lu <wenzhuo.lu@intel.com>

diff --git a/doc/guides/rel_notes/release_20_11.rst b/doc/guides/rel_notes/release_20_11.rst
index 48e4dfd..d9edbcd 100644 (file)
--- a/doc/guides/rel_notes/release_20_11.rst
+++ b/doc/guides/rel_notes/release_20_11.rst
@@ -99,6 +99,10 @@ New Features
   * Changed default link speed to unknown.
   * Added support for 200G link speed.
 
+* **Updated Intel i40e driver.**
+
+  Updated the Intel i40e driver to use write combining stores.
+
 * **Added Ice Lake (Gen4) support for Intel NTB.**
 
   Added NTB device support (4th generation) for Intel Ice Lake platform.

diff --git a/drivers/net/i40e/base/i40e_osdep.h b/drivers/net/i40e/base/i40e_osdep.h
index 58be396..9b50330 100644 (file)
--- a/drivers/net/i40e/base/i40e_osdep.h
+++ b/drivers/net/i40e/base/i40e_osdep.h
@@ -138,6 +138,11 @@ static inline uint32_t i40e_read_addr(volatile void *addr)
 #define I40E_PCI_REG_WRITE_RELAXED(reg, value) \
        rte_write32_relaxed((rte_cpu_to_le_32(value)), reg)
 
+#define I40E_PCI_REG_WC_WRITE(reg, value) \
+       rte_write32_wc((rte_cpu_to_le_32(value)), reg)
+#define I40E_PCI_REG_WC_WRITE_RELAXED(reg, value) \
+       rte_write32_wc_relaxed((rte_cpu_to_le_32(value)), reg)
+
 #define I40E_WRITE_FLUSH(a) I40E_READ_REG(a, I40E_GLGEN_STAT)
 #define I40EVF_WRITE_FLUSH(a) I40E_READ_REG(a, I40E_VFGEN_RSTAT)
 

diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index 322fc1e..f2844d3 100644 (file)
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -760,7 +760,7 @@ i40e_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
        if (nb_hold > rxq->rx_free_thresh) {
                rx_id = (uint16_t) ((rx_id == 0) ?
                        (rxq->nb_rx_desc - 1) : (rx_id - 1));
-               I40E_PCI_REG_WRITE(rxq->qrx_tail, rx_id);
+               I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id);
                nb_hold = 0;
        }
        rxq->nb_rx_hold = nb_hold;
@@ -938,7 +938,7 @@ i40e_recv_scattered_pkts(void *rx_queue,
        if (nb_hold > rxq->rx_free_thresh) {
                rx_id = (uint16_t)(rx_id == 0 ?
                        (rxq->nb_rx_desc - 1) : (rx_id - 1));
-               I40E_PCI_REG_WRITE(rxq->qrx_tail, rx_id);
+               I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id);
                nb_hold = 0;
        }
        rxq->nb_rx_hold = nb_hold;
@@ -1249,7 +1249,7 @@ end_of_tx:
                   (unsigned) tx_id, (unsigned) nb_tx);
 
        rte_io_wmb();
-       I40E_PCI_REG_WRITE_RELAXED(txq->qtx_tail, tx_id);
+       I40E_PCI_REG_WC_WRITE_RELAXED(txq->qtx_tail, tx_id);
        txq->tx_tail = tx_id;
 
        return nb_tx;
@@ -1400,7 +1400,7 @@ tx_xmit_pkts(struct i40e_tx_queue *txq,
                txq->tx_tail = 0;
 
        /* Update the tx tail register */
-       I40E_PCI_REG_WRITE(txq->qtx_tail, txq->tx_tail);
+       I40E_PCI_REG_WC_WRITE(txq->qtx_tail, txq->tx_tail);
 
        return nb_pkts;
 }

diff --git a/drivers/net/i40e/i40e_rxtx_vec_avx2.c b/drivers/net/i40e/i40e_rxtx_vec_avx2.c
index 37e7db5..7a558fc 100644 (file)
--- a/drivers/net/i40e/i40e_rxtx_vec_avx2.c
+++ b/drivers/net/i40e/i40e_rxtx_vec_avx2.c
@@ -134,7 +134,7 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
                             (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);
+       I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id);
 }
 
 #ifndef RTE_LIBRTE_I40E_16BYTE_RX_DESC
@@ -921,7 +921,7 @@ i40e_xmit_fixed_burst_vec_avx2(void *tx_queue, struct rte_mbuf **tx_pkts,
 
        txq->tx_tail = tx_id;
 
-       I40E_PCI_REG_WRITE(txq->qtx_tail, txq->tx_tail);
+       I40E_PCI_REG_WC_WRITE(txq->qtx_tail, txq->tx_tail);
 
        return nb_pkts;
 }

diff --git a/drivers/net/i40e/i40e_rxtx_vec_sse.c b/drivers/net/i40e/i40e_rxtx_vec_sse.c
index 6985183..240ce47 100644 (file)
--- a/drivers/net/i40e/i40e_rxtx_vec_sse.c
+++ b/drivers/net/i40e/i40e_rxtx_vec_sse.c
@@ -86,7 +86,7 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
                             (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);
+       I40E_PCI_REG_WC_WRITE(rxq->qrx_tail, rx_id);
 }
 
 #ifndef RTE_LIBRTE_I40E_16BYTE_RX_DESC
@@ -733,7 +733,7 @@ i40e_xmit_fixed_burst_vec(void *tx_queue, struct rte_mbuf **tx_pkts,
 
        txq->tx_tail = tx_id;
 
-       I40E_PCI_REG_WRITE(txq->qtx_tail, txq->tx_tail);
+       I40E_PCI_REG_WC_WRITE(txq->qtx_tail, txq->tx_tail);
 
        return nb_pkts;
 }