mlx4: reorganize struct mlx4_en_tx_ring
Goal is to reorganize this critical structure to increase performance.
ndo_start_xmit() should only dirty one cache line, and access as few
cache lines as possible.
Add sp_ (Slow Path) prefix to fields that are not used in fast path,
to make clear what is going on.
After this patch pahole reports something much better, as all
ndo_start_xmit() needed fields are packed into two cache lines instead
of seven or eight
struct mlx4_en_tx_ring {
u32 last_nr_txbb; /* 0 0x4 */
u32 cons; /* 0x4 0x4 */
long unsigned int wake_queue; /* 0x8 0x8 */
struct netdev_queue * tx_queue; /* 0x10 0x8 */
u32 (*free_tx_desc)(struct mlx4_en_priv *, struct mlx4_en_tx_ring *, int, u8, u64, int); /* 0x18 0x8 */
struct mlx4_en_rx_ring * recycle_ring; /* 0x20 0x8 */
/* XXX 24 bytes hole, try to pack */
/* --- cacheline 1 boundary (64 bytes) --- */
u32 prod; /* 0x40 0x4 */
unsigned int tx_dropped; /* 0x44 0x4 */
long unsigned int bytes; /* 0x48 0x8 */
long unsigned int packets; /* 0x50 0x8 */
long unsigned int tx_csum; /* 0x58 0x8 */
long unsigned int tso_packets; /* 0x60 0x8 */
long unsigned int xmit_more; /* 0x68 0x8 */
struct mlx4_bf bf; /* 0x70 0x18 */
/* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */
__be32 doorbell_qpn; /* 0x88 0x4 */
__be32 mr_key; /* 0x8c 0x4 */
u32 size; /* 0x90 0x4 */
u32 size_mask; /* 0x94 0x4 */
u32 full_size; /* 0x98 0x4 */
u32 buf_size; /* 0x9c 0x4 */
void * buf; /* 0xa0 0x8 */
struct mlx4_en_tx_info * tx_info; /* 0xa8 0x8 */
int qpn; /* 0xb0 0x4 */
u8 queue_index; /* 0xb4 0x1 */
bool bf_enabled; /* 0xb5 0x1 */
bool bf_alloced; /* 0xb6 0x1 */
u8 hwtstamp_tx_type; /* 0xb7 0x1 */
u8 * bounce_buf; /* 0xb8 0x8 */
/* --- cacheline 3 boundary (192 bytes) --- */
long unsigned int queue_stopped; /* 0xc0 0x8 */
struct mlx4_hwq_resources sp_wqres; /* 0xc8 0x58 */
/* --- cacheline 4 boundary (256 bytes) was 32 bytes ago --- */
struct mlx4_qp sp_qp; /* 0x120 0x30 */
/* --- cacheline 5 boundary (320 bytes) was 16 bytes ago --- */
struct mlx4_qp_context sp_context; /* 0x150 0xf8 */
/* --- cacheline 9 boundary (576 bytes) was 8 bytes ago --- */
cpumask_t sp_affinity_mask; /* 0x248 0x20 */
enum mlx4_qp_state sp_qp_state; /* 0x268 0x4 */
u16 sp_stride; /* 0x26c 0x2 */
u16 sp_cqn; /* 0x26e 0x2 */
/* size: 640, cachelines: 10, members: 36 */
/* sum members: 600, holes: 1, sum holes: 24 */
/* padding: 16 */
};
Instead of this silly placement :
struct mlx4_en_tx_ring {
u32 last_nr_txbb; /* 0 0x4 */
u32 cons; /* 0x4 0x4 */
long unsigned int wake_queue; /* 0x8 0x8 */
/* XXX 48 bytes hole, try to pack */
/* --- cacheline 1 boundary (64 bytes) --- */
u32 prod; /* 0x40 0x4 */
/* XXX 4 bytes hole, try to pack */
long unsigned int bytes; /* 0x48 0x8 */
long unsigned int packets; /* 0x50 0x8 */
long unsigned int tx_csum; /* 0x58 0x8 */
long unsigned int tso_packets; /* 0x60 0x8 */
long unsigned int xmit_more; /* 0x68 0x8 */
unsigned int tx_dropped; /* 0x70 0x4 */
/* XXX 4 bytes hole, try to pack */
struct mlx4_bf bf; /* 0x78 0x18 */
/* --- cacheline 2 boundary (128 bytes) was 16 bytes ago --- */
long unsigned int queue_stopped; /* 0x90 0x8 */
cpumask_t affinity_mask; /* 0x98 0x10 */
struct mlx4_qp qp; /* 0xa8 0x30 */
/* --- cacheline 3 boundary (192 bytes) was 24 bytes ago --- */
struct mlx4_hwq_resources wqres; /* 0xd8 0x58 */
/* --- cacheline 4 boundary (256 bytes) was 48 bytes ago --- */
u32 size; /* 0x130 0x4 */
u32 size_mask; /* 0x134 0x4 */
u16 stride; /* 0x138 0x2 */
/* XXX 2 bytes hole, try to pack */
u32 full_size; /* 0x13c 0x4 */
/* --- cacheline 5 boundary (320 bytes) --- */
u16 cqn; /* 0x140 0x2 */
/* XXX 2 bytes hole, try to pack */
u32 buf_size; /* 0x144 0x4 */
__be32 doorbell_qpn; /* 0x148 0x4 */
__be32 mr_key; /* 0x14c 0x4 */
void * buf; /* 0x150 0x8 */
struct mlx4_en_tx_info * tx_info; /* 0x158 0x8 */
struct mlx4_en_rx_ring * recycle_ring; /* 0x160 0x8 */
u32 (*free_tx_desc)(struct mlx4_en_priv *, struct mlx4_en_tx_ring *, int, u8, u64, int); /* 0x168 0x8 */
u8 * bounce_buf; /* 0x170 0x8 */
struct mlx4_qp_context context; /* 0x178 0xf8 */
/* --- cacheline 9 boundary (576 bytes) was 48 bytes ago --- */
int qpn; /* 0x270 0x4 */
enum mlx4_qp_state qp_state; /* 0x274 0x4 */
u8 queue_index; /* 0x278 0x1 */
bool bf_enabled; /* 0x279 0x1 */
bool bf_alloced; /* 0x27a 0x1 */
/* XXX 5 bytes hole, try to pack */
/* --- cacheline 10 boundary (640 bytes) --- */
struct netdev_queue * tx_queue; /* 0x280 0x8 */
int hwtstamp_tx_type; /* 0x288 0x4 */
/* size: 704, cachelines: 11, members: 36 */
/* sum members: 587, holes: 6, sum holes: 65 */
/* padding: 52 */
};
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
3 files changed