net/mlx5e: Optimize XDP frame xmit

XDP SQ has a fixed size WQE (MLX5E_XDP_TX_WQEBBS = 1) and only posts
one kind of WQE (MLX5_OPCODE_SEND),

Also we initialize SQ descriptors static fields once on open_xdpsq,
rather than every time on critical path.

Optimize the code in light of those facts and add a prefetch of the TX
descriptor first thing in the xdp xmit function.

Performance improvement:
System: Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz

Test case              Before     Now        improvement
---------------------------------------------------------------
XDP TX   (1 core)      13Mpps    13.7Mpps       5%

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 5e4ae94..f02d2cb 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -116,12 +116,8 @@
        (DIV_ROUND_UP(sizeof(struct mlx5e_umr_wqe), MLX5_SEND_WQE_BB))
 
 #define MLX5E_XDP_MIN_INLINE (ETH_HLEN + VLAN_HLEN)
-#define MLX5E_XDP_IHS_DS_COUNT \
-       DIV_ROUND_UP(MLX5E_XDP_MIN_INLINE - 2, MLX5_SEND_WQE_DS)
 #define MLX5E_XDP_TX_DS_COUNT \
        ((sizeof(struct mlx5e_tx_wqe) / MLX5_SEND_WQE_DS) + 1 /* SG DS */)
-#define MLX5E_XDP_TX_WQEBBS \
-       DIV_ROUND_UP(MLX5E_XDP_TX_DS_COUNT, MLX5_SEND_WQEBB_NUM_DS)
 
 #define MLX5E_NUM_MAIN_GROUPS 9
 
@@ -352,7 +348,6 @@ struct mlx5e_sq {
                } txq;
                struct mlx5e_sq_wqe_info *ico_wqe;
                struct {
-                       struct mlx5e_sq_wqe_info  *wqe_info;
                        struct mlx5e_dma_info     *di;
                        bool                       doorbell;
                } xdp;

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 2100331..d39ee66 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -894,7 +894,6 @@ static void mlx5e_close_rq(struct mlx5e_rq *rq)
 static void mlx5e_free_sq_xdp_db(struct mlx5e_sq *sq)
 {
        kfree(sq->db.xdp.di);
-       kfree(sq->db.xdp.wqe_info);
 }
 
 static int mlx5e_alloc_sq_xdp_db(struct mlx5e_sq *sq, int numa)
@@ -903,9 +902,7 @@ static int mlx5e_alloc_sq_xdp_db(struct mlx5e_sq *sq, int numa)
 
        sq->db.xdp.di = kzalloc_node(sizeof(*sq->db.xdp.di) * wq_sz,
                                     GFP_KERNEL, numa);
-       sq->db.xdp.wqe_info = kzalloc_node(sizeof(*sq->db.xdp.wqe_info) * wq_sz,
-                                          GFP_KERNEL, numa);
-       if (!sq->db.xdp.di || !sq->db.xdp.wqe_info) {
+       if (!sq->db.xdp.di) {
                mlx5e_free_sq_xdp_db(sq);
                return -ENOMEM;
        }
@@ -993,7 +990,7 @@ static int mlx5e_sq_get_max_wqebbs(u8 sq_type)
        case MLX5E_SQ_ICO:
                return MLX5E_ICOSQ_MAX_WQEBBS;
        case MLX5E_SQ_XDP:
-               return MLX5E_XDP_TX_WQEBBS;
+               return 1;
        }
        return MLX5_SEND_WQE_MAX_WQEBBS;
 }
@@ -1513,6 +1510,40 @@ static inline int mlx5e_get_max_num_channels(struct mlx5_core_dev *mdev)
                      MLX5E_MAX_NUM_CHANNELS);
 }
 
+static int mlx5e_open_xdpsq(struct mlx5e_channel *c,
+                           struct mlx5e_sq_param *param,
+                           struct mlx5e_sq *sq)
+{
+       unsigned int ds_cnt = MLX5E_XDP_TX_DS_COUNT;
+       unsigned int inline_hdr_sz = 0;
+       int err;
+       int i;
+
+       err = mlx5e_open_sq(c, 0, param, sq);
+       if (err)
+               return err;
+
+       if (sq->min_inline_mode != MLX5_INLINE_MODE_NONE) {
+               inline_hdr_sz = MLX5E_XDP_MIN_INLINE;
+               ds_cnt++;
+       }
+
+       /* Pre initialize fixed WQE fields */
+       for (i = 0; i < mlx5_wq_cyc_get_size(&sq->wq); i++) {
+               struct mlx5e_tx_wqe      *wqe  = mlx5_wq_cyc_get_wqe(&sq->wq, i);
+               struct mlx5_wqe_ctrl_seg *cseg = &wqe->ctrl;
+               struct mlx5_wqe_eth_seg  *eseg = &wqe->eth;
+               struct mlx5_wqe_data_seg *dseg;
+
+               cseg->qpn_ds = cpu_to_be32((sq->sqn << 8) | ds_cnt);
+               eseg->inline_hdr.sz = cpu_to_be16(inline_hdr_sz);
+
+               dseg = (struct mlx5_wqe_data_seg *)cseg + (ds_cnt - 1);
+               dseg->lkey = sq->mkey_be;
+       }
+       return 0;
+}
+
 static int mlx5e_open_channel(struct mlx5e_priv *priv, int ix,
                              struct mlx5e_channel_param *cparam,
                              struct mlx5e_channel **cp)
@@ -1587,7 +1618,7 @@ static int mlx5e_open_channel(struct mlx5e_priv *priv, int ix,
                }
        }
 
-       err = c->xdp ? mlx5e_open_sq(c, 0, &cparam->xdp_sq, &c->rq.xdpsq) : 0;
+       err = c->xdp ? mlx5e_open_xdpsq(c, &cparam->xdp_sq, &c->rq.xdpsq) : 0;
        if (err)
                goto err_close_sqs;
 

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 040074f..1b50c54 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -641,7 +641,7 @@ static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_sq *sq)
 {
        struct mlx5_wq_cyc *wq = &sq->wq;
        struct mlx5e_tx_wqe *wqe;
-       u16 pi = (sq->pc - MLX5E_XDP_TX_WQEBBS) & wq->sz_m1; /* last pi */
+       u16 pi = (sq->pc - 1) & wq->sz_m1; /* last pi */
 
        wqe  = mlx5_wq_cyc_get_wqe(wq, pi);
 
@@ -657,17 +657,17 @@ static inline bool mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
        struct mlx5_wq_cyc       *wq   = &sq->wq;
        u16                      pi    = sq->pc & wq->sz_m1;
        struct mlx5e_tx_wqe      *wqe  = mlx5_wq_cyc_get_wqe(wq, pi);
-       struct mlx5e_sq_wqe_info *wi   = &sq->db.xdp.wqe_info[pi];
 
        struct mlx5_wqe_ctrl_seg *cseg = &wqe->ctrl;
        struct mlx5_wqe_eth_seg  *eseg = &wqe->eth;
        struct mlx5_wqe_data_seg *dseg;
-       u8 ds_cnt = MLX5E_XDP_TX_DS_COUNT;
 
        ptrdiff_t data_offset = xdp->data - xdp->data_hard_start;
        dma_addr_t dma_addr  = di->addr + data_offset;
        unsigned int dma_len = xdp->data_end - xdp->data;
 
+       prefetchw(wqe);
+
        if (unlikely(dma_len < MLX5E_XDP_MIN_INLINE ||
                     MLX5E_SW2HW_MTU(rq->netdev->mtu) < dma_len)) {
                rq->stats.xdp_drop++;
@@ -675,7 +675,7 @@ static inline bool mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
                return false;
        }
 
-       if (unlikely(!mlx5e_sq_has_room_for(sq, MLX5E_XDP_TX_WQEBBS))) {
+       if (unlikely(!mlx5e_sq_has_room_for(sq, 1))) {
                if (sq->db.xdp.doorbell) {
                        /* SQ is full, ring doorbell */
                        mlx5e_xmit_xdp_doorbell(sq);
@@ -686,35 +686,29 @@ static inline bool mlx5e_xmit_xdp_frame(struct mlx5e_rq *rq,
                return false;
        }
 
-       dma_sync_single_for_device(sq->pdev, dma_addr, dma_len,
-                                  PCI_DMA_TODEVICE);
+       dma_sync_single_for_device(sq->pdev, dma_addr, dma_len, PCI_DMA_TODEVICE);
 
-       memset(wqe, 0, sizeof(*wqe));
+       cseg->fm_ce_se = 0;
 
        dseg = (struct mlx5_wqe_data_seg *)eseg + 1;
+
        /* copy the inline part if required */
        if (sq->min_inline_mode != MLX5_INLINE_MODE_NONE) {
                memcpy(eseg->inline_hdr.start, xdp->data, MLX5E_XDP_MIN_INLINE);
                eseg->inline_hdr.sz = cpu_to_be16(MLX5E_XDP_MIN_INLINE);
                dma_len  -= MLX5E_XDP_MIN_INLINE;
                dma_addr += MLX5E_XDP_MIN_INLINE;
-
-               ds_cnt   += MLX5E_XDP_IHS_DS_COUNT;
                dseg++;
        }
 
        /* write the dma part */
        dseg->addr       = cpu_to_be64(dma_addr);
        dseg->byte_count = cpu_to_be32(dma_len);
-       dseg->lkey       = sq->mkey_be;
 
        cseg->opmod_idx_opcode = cpu_to_be32((sq->pc << 8) | MLX5_OPCODE_SEND);
-       cseg->qpn_ds = cpu_to_be32((sq->sqn << 8) | ds_cnt);
 
        sq->db.xdp.di[pi] = *di;
-       wi->opcode     = MLX5_OPCODE_SEND;
-       wi->num_wqebbs = MLX5E_XDP_TX_WQEBBS;
-       sq->pc += MLX5E_XDP_TX_WQEBBS;
+       sq->pc++;
 
        sq->db.xdp.doorbell = true;
        rq->stats.xdp_tx++;
@@ -1023,7 +1017,6 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
                wqe_counter = be16_to_cpu(cqe->wqe_counter);
 
                do {
-                       struct mlx5e_sq_wqe_info *wi;
                        struct mlx5e_dma_info *di;
                        u16 ci;
 
@@ -1031,14 +1024,8 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
 
                        ci = sqcc & sq->wq.sz_m1;
                        di = &sq->db.xdp.di[ci];
-                       wi = &sq->db.xdp.wqe_info[ci];
-
-                       if (unlikely(wi->opcode == MLX5_OPCODE_NOP)) {
-                               sqcc++;
-                               continue;
-                       }
 
-                       sqcc += wi->num_wqebbs;
+                       sqcc++;
                        /* Recycle RX page */
                        mlx5e_page_release(rq, di, true);
                } while (!last_wqe);
@@ -1056,21 +1043,13 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
 void mlx5e_free_xdpsq_descs(struct mlx5e_sq *sq)
 {
        struct mlx5e_rq *rq = container_of(sq, struct mlx5e_rq, xdpsq);
-       struct mlx5e_sq_wqe_info *wi;
        struct mlx5e_dma_info *di;
        u16 ci;
 
        while (sq->cc != sq->pc) {
                ci = sq->cc & sq->wq.sz_m1;
                di = &sq->db.xdp.di[ci];
-               wi = &sq->db.xdp.wqe_info[ci];
-
-               if (wi->opcode == MLX5_OPCODE_NOP) {
-                       sq->cc++;
-                       continue;
-               }
-
-               sq->cc += wi->num_wqebbs;
+               sq->cc++;
 
                mlx5e_page_release(rq, di, false);
        }