On Mon, Oct 30, 2017 at 10:07:27AM +0000, Matan Azrad wrote:
> Since single segment packets shouldn't use additional memory to
> save segments byte count we can prevent additional memory
> unnecessary usage in this case; Prevent loop management.
>
Sorry for asking but I really don't understand the above, can you
reformulate the problem addressed by this patch?
> Call a dedicated function for handling multi segments case.
This sentence is clearer, I'll base my review on what this patch does, not
the reasons behind it.
> Signed-off-by: Matan Azrad <ma...@mellanox.com>
> Signed-off-by: Ophir Munk <ophi...@mellanox.com>
> ---
> drivers/net/mlx4/mlx4_rxtx.c | 247
> +++++++++++++++++++++++++++----------------
> 1 file changed, 158 insertions(+), 89 deletions(-)
>
> diff --git a/drivers/net/mlx4/mlx4_rxtx.c b/drivers/net/mlx4/mlx4_rxtx.c
> index 8ce70d6..8ea8851 100644
> --- a/drivers/net/mlx4/mlx4_rxtx.c
> +++ b/drivers/net/mlx4/mlx4_rxtx.c
> @@ -62,6 +62,9 @@
> #include "mlx4_rxtx.h"
> #include "mlx4_utils.h"
>
> +#define WQE_ONE_DATA_SEG_SIZE \
> + (sizeof(struct mlx4_wqe_ctrl_seg) + sizeof(struct mlx4_wqe_data_seg))
> +
> /**
> * Pointer-value pair structure used in tx_post_send for saving the first
> * DWORD (32 byte) of a TXBB.
> @@ -140,22 +143,19 @@ struct pv {
> * @return
> * 0 on success, -1 on failure.
> */
> -static int
> -mlx4_txq_complete(struct txq *txq)
> +static inline int
While likely harmless, I think the addition of this inline keyword is not
related to this patch.
> +mlx4_txq_complete(struct txq *txq, const unsigned int elts_n,
> + struct mlx4_sq *sq)
Looks like an indentation issue, you should align it to the contents of the
opening "(" to match the coding style of this file.
> {
> unsigned int elts_comp = txq->elts_comp;
> unsigned int elts_tail = txq->elts_tail;
> - const unsigned int elts_n = txq->elts_n;
> struct mlx4_cq *cq = &txq->mcq;
> - struct mlx4_sq *sq = &txq->msq;
> struct mlx4_cqe *cqe;
> uint32_t cons_index = cq->cons_index;
> uint16_t new_index;
> uint16_t nr_txbbs = 0;
> int pkts = 0;
>
> - if (unlikely(elts_comp == 0))
> - return 0;
> /*
> * Traverse over all CQ entries reported and handle each WQ entry
> * reported by them.
> @@ -238,6 +238,122 @@ struct pv {
> return buf->pool;
> }
>
> +static int handle_multi_segs(struct rte_mbuf *buf,
> + struct txq *txq,
> + struct mlx4_wqe_ctrl_seg **pctrl)
How about naming this function in a way that follows the mlx4_something()
convention?
Here's a suggestion based on how this function remains tied to
mlx4_tx_burst():
mlx4_tx_burst_seg()
> +{
> + int wqe_real_size;
> + int nr_txbbs;
> + struct pv *pv = (struct pv *)txq->bounce_buf;
> + struct mlx4_sq *sq = &txq->msq;
> + uint32_t head_idx = sq->head & sq->txbb_cnt_mask;
> + struct mlx4_wqe_ctrl_seg *ctrl;
> + struct mlx4_wqe_data_seg *dseg;
> + uint32_t lkey;
> + uintptr_t addr;
> + uint32_t byte_count;
> + int pv_counter = 0;
> +
> + /* Calculate the needed work queue entry size for this packet. */
> + wqe_real_size = sizeof(struct mlx4_wqe_ctrl_seg) +
> + buf->nb_segs * sizeof(struct mlx4_wqe_data_seg);
> + nr_txbbs = MLX4_SIZE_TO_TXBBS(wqe_real_size);
> + /*
> + * Check that there is room for this WQE in the send queue and that
> + * the WQE size is legal.
> + */
> + if (((sq->head - sq->tail) + nr_txbbs +
> + sq->headroom_txbbs) >= sq->txbb_cnt ||
> + nr_txbbs > MLX4_MAX_WQE_TXBBS) {
> + return -1;
> + }
> +
Extra empty line.
> + /* Get the control and data entries of the WQE. */
> + ctrl = (struct mlx4_wqe_ctrl_seg *)mlx4_get_send_wqe(sq, head_idx);
> + dseg = (struct mlx4_wqe_data_seg *)((uintptr_t)ctrl +
> + sizeof(struct mlx4_wqe_ctrl_seg));
> + *pctrl = ctrl;
> + /* Fill the data segments with buffer information. */
> + struct rte_mbuf *sbuf;
I'm usually fine with mixing declarations and code when there's a good
reason, however in this case there's no point. sbuf could have been defined
with the rest at the beginning of the function.
> +
Extra empty line here as well.
> + for (sbuf = buf; sbuf != NULL; sbuf = sbuf->next, dseg++) {
> + addr = rte_pktmbuf_mtod(sbuf, uintptr_t);
> + rte_prefetch0((volatile void *)addr);
> + /* Handle WQE wraparound. */
> + if (dseg >= (struct mlx4_wqe_data_seg *)sq->eob)
> + dseg = (struct mlx4_wqe_data_seg *)sq->buf;
> + dseg->addr = rte_cpu_to_be_64(addr);
> + /* Memory region key (big endian) for this memory pool. */
> + lkey = mlx4_txq_mp2mr(txq, mlx4_txq_mb2mp(sbuf));
> + dseg->lkey = rte_cpu_to_be_32(lkey);
> +#ifndef NDEBUG
> + /* Calculate the needed work queue entry size for this packet */
> + if (unlikely(dseg->lkey == rte_cpu_to_be_32((uint32_t)-1))) {
> + /* MR does not exist. */
> + DEBUG("%p: unable to get MP <-> MR association",
> + (void *)txq);
> + /*
> + * Restamp entry in case of failure.
> + * Make sure that size is written correctly
> + * Note that we give ownership to the SW, not the HW.
> + */
> + wqe_real_size = sizeof(struct mlx4_wqe_ctrl_seg) +
> + buf->nb_segs * sizeof(struct mlx4_wqe_data_seg);
> + ctrl->fence_size = (wqe_real_size >> 4) & 0x3f;
> + mlx4_txq_stamp_freed_wqe(sq, head_idx,
> + (sq->head & sq->txbb_cnt) ? 0 : 1);
> + return -1;
> + }
> +#endif /* NDEBUG */
> + if (likely(sbuf->data_len)) {
> + byte_count = rte_cpu_to_be_32(sbuf->data_len);
> + } else {
> + /*
> + * Zero length segment is treated as inline segment
> + * with zero data.
> + */
> + byte_count = RTE_BE32(0x80000000);
> + }
> + /*
> + * If the data segment is not at the beginning of a
> + * Tx basic block (TXBB) then write the byte count,
> + * else postpone the writing to just before updating the
> + * control segment.
> + */
> + if ((uintptr_t)dseg & (uintptr_t)(MLX4_TXBB_SIZE - 1)) {
> + /*
> + * Need a barrier here before writing the byte_count
> + * fields to make sure that all the data is visible
> + * before the byte_count field is set.
> + * Otherwise, if the segment begins a new cacheline,
> + * the HCA prefetcher could grab the 64-byte chunk and
> + * get a valid (!= 0xffffffff) byte count but stale
> + * data, and end up sending the wrong data.
> + */
> + rte_io_wmb();
> + dseg->byte_count = byte_count;
> + } else {
> + /*
> + * This data segment starts at the beginning of a new
> + * TXBB, so we need to postpone its byte_count writing
> + * for later.
> + */
> + pv[pv_counter].dseg = dseg;
> + pv[pv_counter++].val = byte_count;
> + }
> + }
> + /* Write the first DWORD of each TXBB save earlier. */
> + if (pv_counter) {
> + /* Need a barrier here before writing the byte_count. */
> + rte_io_wmb();
> + for (--pv_counter; pv_counter >= 0; pv_counter--)
> + pv[pv_counter].dseg->byte_count = pv[pv_counter].val;
> + }
> + /* Fill the control parameters for this packet. */
> + ctrl->fence_size = (wqe_real_size >> 4) & 0x3f;
> +
Extra empty line.
> + return nr_txbbs;
> +}
> /**
> * DPDK callback for Tx.
> *
> @@ -261,10 +377,11 @@ struct pv {
> unsigned int i;
> unsigned int max;
> struct mlx4_sq *sq = &txq->msq;
> - struct pv *pv = (struct pv *)txq->bounce_buf;
> + int nr_txbbs;
>
> assert(txq->elts_comp_cd != 0);
> - mlx4_txq_complete(txq);
> + if (likely(txq->elts_comp != 0))
> + mlx4_txq_complete(txq, elts_n, sq);
> max = (elts_n - (elts_head - txq->elts_tail));
> if (max > elts_n)
> max -= elts_n;
> @@ -283,7 +400,6 @@ struct pv {
> uint32_t owner_opcode = MLX4_OPCODE_SEND;
> struct mlx4_wqe_ctrl_seg *ctrl;
> struct mlx4_wqe_data_seg *dseg;
> - struct rte_mbuf *sbuf;
> union {
> uint32_t flags;
> uint16_t flags16[2];
> @@ -291,10 +407,6 @@ struct pv {
> uint32_t head_idx = sq->head & sq->txbb_cnt_mask;
> uint32_t lkey;
> uintptr_t addr;
> - uint32_t byte_count;
> - int wqe_real_size;
> - int nr_txbbs;
> - int pv_counter = 0;
>
> /* Clean up old buffer. */
> if (likely(elt->buf != NULL)) {
> @@ -313,40 +425,29 @@ struct pv {
> } while (tmp != NULL);
> }
> RTE_MBUF_PREFETCH_TO_FREE(elt_next->buf);
> -
> - /*
> - * Calculate the needed work queue entry size
> - * for this packet.
> - */
> - wqe_real_size = sizeof(struct mlx4_wqe_ctrl_seg) +
> - buf->nb_segs * sizeof(struct mlx4_wqe_data_seg);
> - nr_txbbs = MLX4_SIZE_TO_TXBBS(wqe_real_size);
> - /*
> - * Check that there is room for this WQE in the send
> - * queue and that the WQE size is legal.
> - */
> - if (((sq->head - sq->tail) + nr_txbbs +
> - sq->headroom_txbbs) >= sq->txbb_cnt ||
> - nr_txbbs > MLX4_MAX_WQE_TXBBS) {
> - elt->buf = NULL;
> - break;
> - }
> - /* Get the control and data entries of the WQE. */
> - ctrl = (struct mlx4_wqe_ctrl_seg *)
> - mlx4_get_send_wqe(sq, head_idx);
> - dseg = (struct mlx4_wqe_data_seg *)((uintptr_t)ctrl +
> - sizeof(struct mlx4_wqe_ctrl_seg));
> - /* Fill the data segments with buffer information. */
> - for (sbuf = buf; sbuf != NULL; sbuf = sbuf->next, dseg++) {
> - addr = rte_pktmbuf_mtod(sbuf, uintptr_t);
> + if (buf->nb_segs == 1) {
> + /*
> + * Check that there is room for this WQE in the send
> + * queue and that the WQE size is legal
> + */
> + if (((sq->head - sq->tail) + 1 + sq->headroom_txbbs) >=
> + sq->txbb_cnt || 1 > MLX4_MAX_WQE_TXBBS) {
> + elt->buf = NULL;
> + break;
> + }
> + /* Get the control and data entries of the WQE. */
> + ctrl = (struct mlx4_wqe_ctrl_seg *)
> + mlx4_get_send_wqe(sq, head_idx);
> + dseg = (struct mlx4_wqe_data_seg *)((uintptr_t)ctrl +
> + sizeof(struct mlx4_wqe_ctrl_seg));
> + addr = rte_pktmbuf_mtod(buf, uintptr_t);
> rte_prefetch0((volatile void *)addr);
> /* Handle WQE wraparound. */
> - if (unlikely(dseg >=
> - (struct mlx4_wqe_data_seg *)sq->eob))
> + if (dseg >= (struct mlx4_wqe_data_seg *)sq->eob)
Ideally this change should have been on its own in a fix commit.
> dseg = (struct mlx4_wqe_data_seg *)sq->buf;
> dseg->addr = rte_cpu_to_be_64(addr);
> /* Memory region key (big endian). */
> - lkey = mlx4_txq_mp2mr(txq, mlx4_txq_mb2mp(sbuf));
> + lkey = mlx4_txq_mp2mr(txq, mlx4_txq_mb2mp(buf));
> dseg->lkey = rte_cpu_to_be_32(lkey);
> #ifndef NDEBUG
> if (unlikely(dseg->lkey ==
> @@ -360,61 +461,28 @@ struct pv {
> * Note that we give ownership to the SW,
> * not the HW.
> */
> - ctrl->fence_size = (wqe_real_size >> 4) & 0x3f;
> + ctrl->fence_size =
> + (WQE_ONE_DATA_SEG_SIZE >> 4) & 0x3f;
> mlx4_txq_stamp_freed_wqe(sq, head_idx,
> (sq->head & sq->txbb_cnt) ? 0 : 1);
> elt->buf = NULL;
> break;
> }
> #endif /* NDEBUG */
> - if (likely(sbuf->data_len)) {
> - byte_count = rte_cpu_to_be_32(sbuf->data_len);
> - } else {
> - /*
> - * Zero length segment is treated as inline
> - * segment with zero data.
> - */
> - byte_count = RTE_BE32(0x80000000);
> - }
> - /*
> - * If the data segment is not at the beginning
> - * of a Tx basic block (TXBB) then write the
> - * byte count, else postpone the writing to
> - * just before updating the control segment.
> - */
> - if ((uintptr_t)dseg & (uintptr_t)(MLX4_TXBB_SIZE - 1)) {
> - /*
> - * Need a barrier here before writing the
> - * byte_count fields to make sure that all the
> - * data is visible before the byte_count field
> - * is set. otherwise, if the segment begins a
> - * new cacheline, the HCA prefetcher could grab
> - * the 64-byte chunk and get a valid
> - * (!= 0xffffffff) byte count but stale data,
> - * and end up sending the wrong data.
> - */
> - rte_io_wmb();
> - dseg->byte_count = byte_count;
> - } else {
> - /*
> - * This data segment starts at the beginning of
> - * a new TXBB, so we need to postpone its
> - * byte_count writing for later.
> - */
> - pv[pv_counter].dseg = dseg;
> - pv[pv_counter++].val = byte_count;
> - }
> - }
> - /* Write the first DWORD of each TXBB save earlier. */
> - if (pv_counter) {
> - /* Need a barrier before writing the byte_count. */
> + /* Need a barrier here before byte count store. */
> rte_io_wmb();
> - for (--pv_counter; pv_counter >= 0; pv_counter--)
> - pv[pv_counter].dseg->byte_count =
> - pv[pv_counter].val;
> + dseg->byte_count = rte_cpu_to_be_32(buf->data_len);
> +
Extra empty line.
> + /* Fill the control parameters for this packet. */
> + ctrl->fence_size = (WQE_ONE_DATA_SEG_SIZE >> 4) & 0x3f;
> + nr_txbbs = 1;
> + } else {
> + nr_txbbs = handle_multi_segs(buf, txq, &ctrl);
> + if (nr_txbbs < 0) {
> + elt->buf = NULL;
> + break;
> + }
> }
> - /* Fill the control parameters for this packet. */
> - ctrl->fence_size = (wqe_real_size >> 4) & 0x3f;
> /*
> * For raw Ethernet, the SOLICIT flag is used to indicate
> * that no ICRC should be calculated.
> @@ -469,6 +537,7 @@ struct pv {
> ctrl->owner_opcode = rte_cpu_to_be_32(owner_opcode |
> ((sq->head & sq->txbb_cnt) ?
> MLX4_BIT_WQE_OWN : 0));
> +
Extra empty line.
> sq->head += nr_txbbs;
> elt->buf = buf;
> bytes_sent += buf->pkt_len;
> --
> 1.8.3.1
>
--
Adrien Mazarguil
6WIND
