Use a non-volatile uint64_t pointer to store to the descriptor ring. This will allow the compiler to optionally merge the stores as it sees best.
Signed-off-by: Bruce Richardson <[email protected]> --- drivers/net/intel/common/tx_scalar.h | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/drivers/net/intel/common/tx_scalar.h b/drivers/net/intel/common/tx_scalar.h index f6ed11a5a8..00771402f8 100644 --- a/drivers/net/intel/common/tx_scalar.h +++ b/drivers/net/intel/common/tx_scalar.h @@ -166,6 +166,19 @@ struct ci_timestamp_queue_fns { write_ts_tail_t write_ts_tail; }; +static inline void +write_txd(volatile void *txd, uint64_t qw0, uint64_t qw1) +{ + /* we use an aligned structure and cast away the volatile to allow the compiler + * to opportunistically optimize the two 64-bit writes as a single 128-bit write. + */ + __rte_aligned(16) struct txdesc { + uint64_t qw0, qw1; + } *txdesc = RTE_CAST_PTR(struct txdesc *, txd); + txdesc->qw0 = rte_cpu_to_le_64(qw0); + txdesc->qw1 = rte_cpu_to_le_64(qw1); +} + static inline uint16_t ci_xmit_pkts(struct ci_tx_queue *txq, struct rte_mbuf **tx_pkts, @@ -299,8 +312,7 @@ ci_xmit_pkts(struct ci_tx_queue *txq, txe->mbuf = NULL; } - ctx_txd[0] = cd_qw0; - ctx_txd[1] = cd_qw1; + write_txd(ctx_txd, cd_qw0, cd_qw1); txe->last_id = tx_last; tx_id = txe->next_id; @@ -347,12 +359,12 @@ ci_xmit_pkts(struct ci_tx_queue *txq, while ((ol_flags & (RTE_MBUF_F_TX_TCP_SEG | RTE_MBUF_F_TX_UDP_SEG)) && unlikely(slen > CI_MAX_DATA_PER_TXD)) { - txd->buffer_addr = rte_cpu_to_le_64(buf_dma_addr); - txd->cmd_type_offset_bsz = rte_cpu_to_le_64(CI_TX_DESC_DTYPE_DATA | + const uint64_t cmd_type_offset_bsz = CI_TX_DESC_DTYPE_DATA | ((uint64_t)td_cmd << CI_TXD_QW1_CMD_S) | ((uint64_t)td_offset << CI_TXD_QW1_OFFSET_S) | ((uint64_t)CI_MAX_DATA_PER_TXD << CI_TXD_QW1_TX_BUF_SZ_S) | - ((uint64_t)td_tag << CI_TXD_QW1_L2TAG1_S)); + ((uint64_t)td_tag << CI_TXD_QW1_L2TAG1_S); + write_txd(txd, buf_dma_addr, cmd_type_offset_bsz); buf_dma_addr += CI_MAX_DATA_PER_TXD; slen -= CI_MAX_DATA_PER_TXD; @@ -368,12 +380,12 @@ ci_xmit_pkts(struct ci_tx_queue *txq, if (m_seg->next == NULL) td_cmd |= CI_TX_DESC_CMD_EOP; - txd->buffer_addr = rte_cpu_to_le_64(buf_dma_addr); - txd->cmd_type_offset_bsz = rte_cpu_to_le_64(CI_TX_DESC_DTYPE_DATA | + const uint64_t cmd_type_offset_bsz = CI_TX_DESC_DTYPE_DATA | ((uint64_t)td_cmd << CI_TXD_QW1_CMD_S) | ((uint64_t)td_offset << CI_TXD_QW1_OFFSET_S) | ((uint64_t)slen << CI_TXD_QW1_TX_BUF_SZ_S) | - ((uint64_t)td_tag << CI_TXD_QW1_L2TAG1_S)); + ((uint64_t)td_tag << CI_TXD_QW1_L2TAG1_S); + write_txd(txd, buf_dma_addr, cmd_type_offset_bsz); txe->last_id = tx_last; tx_id = txe->next_id; -- 2.51.0
