net/mlx5: DR, Limit STE hash table enlarge based on bytemask

When an ste hash table has too many collision we enlarge it
to a bigger hash table (rehash). Rehashing collision improvement
depends on the bytemask value. The more 1 bits we have in bytemask
means better spreading in the table.

Without this fix tables can grow in size without providing any
improvement which can lead to memory depletion and failures.

This patch will limit table rehash to reduce memory and improve
the performance.

Fixes: 41d07074154c ("net/mlx5: DR, Expose steering rule functionality")
Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
index 5dcb8baf491a..bd1699e62142 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
@@ -595,6 +595,18 @@ static void dr_rule_clean_rule_members(struct mlx5dr_rule *rule,
 	}
 }
 
+static u16 dr_get_bits_per_mask(u16 byte_mask)
+{
+	u16 bits = 0;
+
+	while (byte_mask) {
+		byte_mask = byte_mask & (byte_mask - 1);
+		bits++;
+	}
+
+	return bits;
+}
+
 static bool dr_rule_need_enlarge_hash(struct mlx5dr_ste_htbl *htbl,
 				      struct mlx5dr_domain *dmn,
 				      struct mlx5dr_domain_rx_tx *nic_dmn)
@@ -607,6 +619,9 @@ static bool dr_rule_need_enlarge_hash(struct mlx5dr_ste_htbl *htbl,
 	if (!ctrl->may_grow)
 		return false;
 
+	if (dr_get_bits_per_mask(htbl->byte_mask) * BITS_PER_BYTE <= htbl->chunk_size)
+		return false;
+
 	if (ctrl->num_of_collisions >= ctrl->increase_threshold &&
 	    (ctrl->num_of_valid_entries - ctrl->num_of_collisions) >= ctrl->increase_threshold)
 		return true;