net/mlx5e: Early-return on empty completion queues

NAPI context handles different kinds of completion queues
(RX, TX, and others). Hence, upon a poll trial, some of them
might be empty.
Here we early-return upon empty completion queues, as well as
full rx buffer, and save unnecessary logic and memory barriers.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 8af6577..ab1213a 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -459,16 +459,19 @@ void mlx5e_dealloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq)
 {
        struct mlx5_wq_ll *wq = &rq->wq;
+       int err;
 
        if (unlikely(!test_bit(MLX5E_RQ_STATE_ENABLED, &rq->state)))
                return false;
 
+       if (mlx5_wq_ll_is_full(wq))
+               return false;
+
        if (test_bit(MLX5E_RQ_STATE_UMR_WQE_IN_PROGRESS, &rq->state))
                return true;
 
-       while (!mlx5_wq_ll_is_full(wq)) {
+       do {
                struct mlx5e_rx_wqe *wqe = mlx5_wq_ll_get_wqe(wq, wq->head);
-               int err;
 
                err = rq->alloc_wqe(rq, wqe, wq->head);
                if (err == -EBUSY)
@@ -479,14 +482,14 @@ bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq)
                }
 
                mlx5_wq_ll_push(wq, be16_to_cpu(wqe->next.next_wqe_index));
-       }
+       } while (!mlx5_wq_ll_is_full(wq));
 
        /* ensure wqes are visible to device before updating doorbell record */
        dma_wmb();
 
        mlx5_wq_ll_update_db_record(wq);
 
-       return !mlx5_wq_ll_is_full(wq);
+       return !!err;
 }
 
 static void mlx5e_lro_update_hdr(struct sk_buff *skb, struct mlx5_cqe64 *cqe,
@@ -981,7 +984,8 @@ mpwrq_cqe_out:
 int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
 {
        struct mlx5e_rq *rq = container_of(cq, struct mlx5e_rq, cq);
-       struct mlx5e_xdpsq *xdpsq = &rq->xdpsq;
+       struct mlx5e_xdpsq *xdpsq;
+       struct mlx5_cqe64 *cqe;
        int work_done = 0;
 
        if (unlikely(!test_bit(MLX5E_RQ_STATE_ENABLED, &rq->state)))
@@ -990,12 +994,13 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
        if (cq->decmprs_left)
                work_done += mlx5e_decompress_cqes_cont(rq, cq, 0, budget);
 
-       for (; work_done < budget; work_done++) {
-               struct mlx5_cqe64 *cqe = mlx5_cqwq_get_cqe(&cq->wq);
+       cqe = mlx5_cqwq_get_cqe(&cq->wq);
+       if (!cqe)
+               return 0;
 
-               if (!cqe)
-                       break;
+       xdpsq = &rq->xdpsq;
 
+       do {
                if (mlx5_get_cqe_format(cqe) == MLX5_COMPRESSED) {
                        work_done +=
                                mlx5e_decompress_cqes_start(rq, cq,
@@ -1006,7 +1011,7 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
                mlx5_cqwq_pop(&cq->wq);
 
                rq->handle_rx_cqe(rq, cqe);
-       }
+       } while ((++work_done < budget) && (cqe = mlx5_cqwq_get_cqe(&cq->wq)));
 
        if (xdpsq->db.doorbell) {
                mlx5e_xmit_xdp_doorbell(xdpsq);
@@ -1024,6 +1029,7 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget)
 bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
 {
        struct mlx5e_xdpsq *sq;
+       struct mlx5_cqe64 *cqe;
        struct mlx5e_rq *rq;
        u16 sqcc;
        int i;
@@ -1033,6 +1039,10 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
        if (unlikely(!test_bit(MLX5E_SQ_STATE_ENABLED, &sq->state)))
                return false;
 
+       cqe = mlx5_cqwq_get_cqe(&cq->wq);
+       if (!cqe)
+               return false;
+
        rq = container_of(sq, struct mlx5e_rq, xdpsq);
 
        /* sq->cc must be updated only after mlx5_cqwq_update_db_record(),
@@ -1040,15 +1050,11 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
         */
        sqcc = sq->cc;
 
-       for (i = 0; i < MLX5E_TX_CQ_POLL_BUDGET; i++) {
-               struct mlx5_cqe64 *cqe;
+       i = 0;
+       do {
                u16 wqe_counter;
                bool last_wqe;
 
-               cqe = mlx5_cqwq_get_cqe(&cq->wq);
-               if (!cqe)
-                       break;
-
                mlx5_cqwq_pop(&cq->wq);
 
                wqe_counter = be16_to_cpu(cqe->wqe_counter);
@@ -1066,7 +1072,7 @@ bool mlx5e_poll_xdpsq_cq(struct mlx5e_cq *cq)
                        /* Recycle RX page */
                        mlx5e_page_release(rq, di, true);
                } while (!last_wqe);
-       }
+       } while ((++i < MLX5E_TX_CQ_POLL_BUDGET) && (cqe = mlx5_cqwq_get_cqe(&cq->wq)));
 
        mlx5_cqwq_update_db_record(&cq->wq);
 

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
index 31353e5..80d2121 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
@@ -394,6 +394,7 @@ netdev_tx_t mlx5e_xmit(struct sk_buff *skb, struct net_device *dev)
 bool mlx5e_poll_tx_cq(struct mlx5e_cq *cq, int napi_budget)
 {
        struct mlx5e_txqsq *sq;
+       struct mlx5_cqe64 *cqe;
        u32 dma_fifo_cc;
        u32 nbytes;
        u16 npkts;
@@ -405,6 +406,10 @@ bool mlx5e_poll_tx_cq(struct mlx5e_cq *cq, int napi_budget)
        if (unlikely(!test_bit(MLX5E_SQ_STATE_ENABLED, &sq->state)))
                return false;
 
+       cqe = mlx5_cqwq_get_cqe(&cq->wq);
+       if (!cqe)
+               return false;
+
        npkts = 0;
        nbytes = 0;
 
@@ -416,15 +421,11 @@ bool mlx5e_poll_tx_cq(struct mlx5e_cq *cq, int napi_budget)
        /* avoid dirtying sq cache line every cqe */
        dma_fifo_cc = sq->dma_fifo_cc;
 
-       for (i = 0; i < MLX5E_TX_CQ_POLL_BUDGET; i++) {
-               struct mlx5_cqe64 *cqe;
+       i = 0;
+       do {
                u16 wqe_counter;
                bool last_wqe;
 
-               cqe = mlx5_cqwq_get_cqe(&cq->wq);
-               if (!cqe)
-                       break;
-
                mlx5_cqwq_pop(&cq->wq);
 
                wqe_counter = be16_to_cpu(cqe->wqe_counter);
@@ -467,7 +468,8 @@ bool mlx5e_poll_tx_cq(struct mlx5e_cq *cq, int napi_budget)
                        sqcc += wi->num_wqebbs;
                        napi_consume_skb(skb, napi_budget);
                } while (!last_wqe);
-       }
+
+       } while ((++i < MLX5E_TX_CQ_POLL_BUDGET) && (cqe = mlx5_cqwq_get_cqe(&cq->wq)));
 
        mlx5_cqwq_update_db_record(&cq->wq);