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net/mlx5: Pack mlx5_rl_entry structure
authorParav Pandit <parav@nvidia.com>
Fri, 19 Feb 2021 06:18:12 +0000 (08:18 +0200)
committerSaeed Mahameed <saeedm@nvidia.com>
Fri, 2 Apr 2021 23:13:05 +0000 (16:13 -0700)
commit4c4c0a89abd5c08e91df9bcce4ebcb3433bbb9bf
tree22aee394130654101d7a663be8a07b3896c52565
parentc6baac47d9e64d42f98ef745ed1f2925efc78440
net/mlx5: Pack mlx5_rl_entry structure

mlx5_rl_entry structure is not properly packed as shown below. Due to this
an array of size 9144 bytes allocated which is aligned to 16Kbytes.
Hence, pack the structure and avoid the wastage.

This offers 8Kbytes of saving per mlx5_core_dev struct.

pahole -C mlx5_rl_entry  drivers/net/ethernet/mellanox/mlx5/core/en_main.o

Existing layout:

struct mlx5_rl_entry {
        u8                         rl_raw[48];           /*     0    48 */
        u16                        index;                /*    48     2 */

        /* XXX 6 bytes hole, try to pack */

        u64                        refcount;             /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        u16                        uid;                  /*    64     2 */
        u8                         dedicated:1;          /*    66: 0  1 */

        /* size: 72, cachelines: 2, members: 5 */
        /* sum members: 60, holes: 1, sum holes: 6 */
        /* sum bitfield members: 1 bits (0 bytes) */
        /* padding: 5 */
        /* bit_padding: 7 bits */
        /* last cacheline: 8 bytes */
};

After alignment:

struct mlx5_rl_entry {
        u8                         rl_raw[48];           /*     0    48 */
        u64                        refcount;             /*    48     8 */
        u16                        index;                /*    56     2 */
        u16                        uid;                  /*    58     2 */
        u8                         dedicated:1;          /*    60: 0  1 */

        /* size: 64, cachelines: 1, members: 5 */
        /* padding: 3 */
        /* bit_padding: 7 bits */
};

Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
include/linux/mlx5/driver.h