netdev - [net-next 11/16] net/mlx5: E-Switch, cut down mlx5_vport

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Date:   Sat,  3 Apr 2021 21:19:49 -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>,
        Parav Pandit <parav@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: [net-next 11/16] net/mlx5: E-Switch, cut down mlx5_vport_info structure size by 8 bytes

From: Parav Pandit <parav@...dia.com>

Structure mlx5_vport_info consumes 40 bytes of space due to a hole
in it. After packing it reduces to 32 bytes.

Currently:
pahole -C mlx5_vport_info drivers/net/ethernet/mellanox/mlx5/core/eswitch.o
struct mlx5_vport_info {
        u8                         mac[6];               /*     0     6 */
        u16                        vlan;                 /*     6     2 */
        u8                         qos;                  /*     8     1 */

        /* XXX 7 bytes hole, try to pack */

        u64                        node_guid;            /*    16     8 */
        int                        link_state;           /*    24     4 */
        u32                        min_rate;             /*    28     4 */
        u32                        max_rate;             /*    32     4 */
        bool                       spoofchk;             /*    36     1 */
        bool                       trusted;              /*    37     1 */

        /* size: 40, cachelines: 1, members: 9 */
        /* sum members: 31, holes: 1, sum holes: 7 */
        /* padding: 2 */
        /* last cacheline: 40 bytes */
};

After packing:

$ pahole -C mlx5_vport_info drivers/net/ethernet/mellanox/mlx5/core/eswitch.o

struct mlx5_vport_info {
        u8                         mac[6];               /*     0     6 */
        u16                        vlan;                 /*     6     2 */
        u64                        node_guid;            /*     8     8 */
        int                        link_state;           /*    16     4 */
        u32                        min_rate;             /*    20     4 */
        u32                        max_rate;             /*    24     4 */
        u8                         qos;                  /*    28     1 */
        u8                         spoofchk:1;           /*    29: 0  1 */
        u8                         trusted:1;            /*    29: 1  1 */

        /* size: 32, cachelines: 1, members: 9 */
        /* padding: 2 */
        /* bit_padding: 6 bits */
        /* last cacheline: 32 bytes */
};

Signed-off-by: Parav Pandit <parav@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/eswitch.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
index 64db903068c1..5d50b127f81a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
@@ -120,6 +120,8 @@ struct mlx5_vport_info {
 	u16                     vlan;
 	u64                     node_guid;
 	int                     link_state;
+	u32                     min_rate;
+	u32                     max_rate;
 	u8                      qos;
 	u8                      spoofchk: 1;
 	u8                      trusted: 1;
-- 
2.30.2