mlx5: adapt indirection table size depending on Rx queues number

Use the maximum size of the indirection table when the number of requested
RX queues is not a power of two, this help to improve RSS balancing.

A message informs users that balancing is not optimal in such cases.

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index e394d32..4413248 100644 (file)
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -299,7 +299,9 @@ mlx5_pci_devinit(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
                struct ether_addr mac;
 
 #ifdef HAVE_EXP_QUERY_DEVICE
-               exp_device_attr.comp_mask = IBV_EXP_DEVICE_ATTR_EXP_CAP_FLAGS;
+               exp_device_attr.comp_mask =
+                       IBV_EXP_DEVICE_ATTR_EXP_CAP_FLAGS |
+                       IBV_EXP_DEVICE_ATTR_RX_HASH;
 #endif /* HAVE_EXP_QUERY_DEVICE */
 
                DEBUG("using port %u (%08" PRIx32 ")", port, test);
@@ -363,6 +365,12 @@ mlx5_pci_devinit(struct rte_pci_driver *pci_drv, struct rte_pci_device *pci_dev)
                DEBUG("L2 tunnel checksum offloads are %ssupported",
                      (priv->hw_csum_l2tun ? "" : "not "));
 
+               priv->ind_table_max_size = exp_device_attr.rx_hash_caps.max_rwq_indirection_table_size;
+               DEBUG("maximum RX indirection table size is %u",
+                     priv->ind_table_max_size);
+
+#else /* HAVE_EXP_QUERY_DEVICE */
+               priv->ind_table_max_size = RSS_INDIRECTION_TABLE_SIZE;
 #endif /* HAVE_EXP_QUERY_DEVICE */
 
                priv->vf = vf;

diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index 29fc1da..5a41678 100644 (file)
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -109,6 +109,7 @@ struct priv {
        /* Indirection tables referencing all RX WQs. */
        struct ibv_exp_rwq_ind_table *(*ind_tables)[];
        unsigned int ind_tables_n; /* Number of indirection tables. */
+       unsigned int ind_table_max_size; /* Maximum indirection table size. */
        /* Hash RX QPs feeding the indirection table. */
        struct hash_rxq (*hash_rxqs)[];
        unsigned int hash_rxqs_n; /* Hash RX QPs array size. */

diff --git a/drivers/net/mlx5/mlx5_defs.h b/drivers/net/mlx5/mlx5_defs.h
index 369f8b6..3952c71 100644 (file)
--- a/drivers/net/mlx5/mlx5_defs.h
+++ b/drivers/net/mlx5/mlx5_defs.h
@@ -46,6 +46,9 @@
 /* Request send completion once in every 64 sends, might be less. */
 #define MLX5_PMD_TX_PER_COMP_REQ 64
 
+/* RSS Indirection table size. */
+#define RSS_INDIRECTION_TABLE_SIZE 128
+
 /* Maximum number of Scatter/Gather Elements per Work Request. */
 #ifndef MLX5_PMD_SGE_WR_N
 #define MLX5_PMD_SGE_WR_N 4

diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 8ea1267..41f8811 100644 (file)
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -224,7 +224,13 @@ priv_make_ind_table_init(struct priv *priv,
 int
 priv_create_hash_rxqs(struct priv *priv)
 {
-       unsigned int wqs_n = (1 << log2above(priv->rxqs_n));
+       /* If the requested number of WQs is not a power of two, use the
+        * maximum indirection table size for better balancing.
+        * The result is always rounded to the next power of two. */
+       unsigned int wqs_n =
+               (1 << log2above((priv->rxqs_n & (priv->rxqs_n - 1)) ?
+                               priv->ind_table_max_size :
+                               priv->rxqs_n));
        struct ibv_exp_wq *wqs[wqs_n];
        struct ind_table_init ind_table_init[IND_TABLE_INIT_N];
        unsigned int ind_tables_n =
@@ -251,16 +257,17 @@ priv_create_hash_rxqs(struct priv *priv)
                      " indirection table cannot be created");
                return EINVAL;
        }
-       if (wqs_n < priv->rxqs_n) {
+       if ((wqs_n < priv->rxqs_n) || (wqs_n > priv->ind_table_max_size)) {
                ERROR("cannot handle this many RX queues (%u)", priv->rxqs_n);
                err = ERANGE;
                goto error;
        }
-       if (wqs_n != priv->rxqs_n)
-               WARN("%u RX queues are configured, consider rounding this"
-                    " number to the next power of two (%u) for optimal"
-                    " performance",
-                    priv->rxqs_n, wqs_n);
+       if (wqs_n != priv->rxqs_n) {
+               INFO("%u RX queues are configured, consider rounding this"
+                    " number to the next power of two for better balancing",
+                    priv->rxqs_n);
+               DEBUG("indirection table extended to assume %u WQs", wqs_n);
+       }
        /* When the number of RX queues is not a power of two, the remaining
         * table entries are padded with reused WQs and hashes are not spread
         * uniformly. */