netdev - [net-next 17/17] net/mlx5: Improve performance in SF allocation

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Message-Id: <20210527043609.654854-18-saeed@kernel.org>
Date:   Wed, 26 May 2021 21:36:09 -0700
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...dia.com>,
        Eli Cohen <elic@...dia.com>, Saeed Mahameed <saeedm@...dia.com>
Subject: [net-next 17/17] net/mlx5: Improve performance in SF allocation

From: Eli Cohen <elic@...dia.com>

Avoid second traversal on the SF table by recording the first free entry
and using it in case the looked up entry was not found in the table.

Signed-off-by: Eli Cohen <elic@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 .../ethernet/mellanox/mlx5/core/sf/hw_table.c | 23 +++++++++++--------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/sf/hw_table.c b/drivers/net/ethernet/mellanox/mlx5/core/sf/hw_table.c
index ef5f892aafad..0c1fbf711fe6 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/sf/hw_table.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/sf/hw_table.c
@@ -74,26 +74,29 @@ static int mlx5_sf_hw_table_id_alloc(struct mlx5_sf_hw_table *table, u32 control
 				     u32 usr_sfnum)
 {
 	struct mlx5_sf_hwc_table *hwc;
+	int free_idx = -1;
 	int i;
 
 	hwc = mlx5_sf_controller_to_hwc(table->dev, controller);
 	if (!hwc->sfs)
 		return -ENOSPC;
 
-	/* Check if sf with same sfnum already exists or not. */
-	for (i = 0; i < hwc->max_fn; i++) {
-		if (hwc->sfs[i].allocated && hwc->sfs[i].usr_sfnum == usr_sfnum)
-			return -EEXIST;
-	}
-	/* Find the free entry and allocate the entry from the array */
 	for (i = 0; i < hwc->max_fn; i++) {
 		if (!hwc->sfs[i].allocated) {
-			hwc->sfs[i].usr_sfnum = usr_sfnum;
-			hwc->sfs[i].allocated = true;
-			return i;
+			free_idx = free_idx == -1 ? i : -1;
+			continue;
 		}
+
+		if (hwc->sfs[i].usr_sfnum == usr_sfnum)
+			return -EEXIST;
 	}
-	return -ENOSPC;
+
+	if (free_idx == -1)
+		return -ENOSPC;
+
+	hwc->sfs[free_idx].usr_sfnum = usr_sfnum;
+	hwc->sfs[free_idx].allocated = true;
+	return 0;
 }
 
 static void mlx5_sf_hw_table_id_free(struct mlx5_sf_hw_table *table, u32 controller, int id)
-- 
2.31.1