[PATCH 4.15 006/163] IB/core: Fix ib_wc structure size to remain in 64 bytes boundary

Greg Kroah-Hartman
2018-02-21T12:47:15Z

From: Bodong Wang <bodong@mellanox.com>

commit cd2a6e7d384b043d5d029e39663061cebc949385 upstream.

The change of slid from u16 to u32 results in sizeof(struct ib_wc)
cross 64B boundary, which causes more cache misses. This patch
rearranges the fields and remain the size to 64B.

Pahole output before this change:

struct ib_wc {
union {
u64 wr_id; /* 8 */
struct ib_cqe * wr_cqe; /* 8 */
}; /* 0 8 */
enum ib_wc_status status; /* 8 4 */
enum ib_wc_opcode opcode; /* 12 4 */
u32 vendor_err; /* 16 4 */
u32 byte_len; /* 20 4 */
struct ib_qp * qp; /* 24 8 */
union {
__be32 imm_data; /* 4 */
u32 invalidate_rkey; /* 4 */
} ex; /* 32 4 */
u32 src_qp; /* 36 4 */
int wc_flags; /* 40 4 */
u16 pkey_index; /* 44 2 */

/* XXX 2 bytes hole, try to pack */

u32 slid; /* 48 4 */
u8 sl; /* 52 1 */
u8 dlid_path_bits; /* 53 1 */
u8 port_num; /* 54 1 */
u8 smac[6]; /* 55 6 */

/* XXX 1 byte hole, try to pack */

u16 vlan_id; /* 62 2 */
/* --- cacheline 1 boundary (64 bytes) --- */
u8 network_hdr_type; /* 64 1 */

/* size: 72, cachelines: 2, members: 17 */
/* sum members: 62, holes: 2, sum holes: 3 */
/* padding: 7 */
/* last cacheline: 8 bytes */
};

Pahole output after this change:

struct ib_wc {
union {
u64 wr_id; /* 8 */
struct ib_cqe * wr_cqe; /* 8 */
}; /* 0 8 */
enum ib_wc_status status; /* 8 4 */
enum ib_wc_opcode opcode; /* 12 4 */
u32 vendor_err; /* 16 4 */
u32 byte_len; /* 20 4 */
struct ib_qp * qp; /* 24 8 */
union {
__be32 imm_data; /* 4 */
u32 invalidate_rkey; /* 4 */
} ex; /* 32 4 */
u32 src_qp; /* 36 4 */
u32 slid; /* 40 4 */
int wc_flags; /* 44 4 */
u16 pkey_index; /* 48 2 */
u8 sl; /* 50 1 */
u8 dlid_path_bits; /* 51 1 */
u8 port_num; /* 52 1 */
u8 smac[6]; /* 53 6 */

/* XXX 1 byte hole, try to pack */

u16 vlan_id; /* 60 2 */
u8 network_hdr_type; /* 62 1 */

/* size: 64, cachelines: 1, members: 17 */
/* sum members: 62, holes: 1, sum holes: 1 */
/* padding: 1 */
};

Fixes: 7db20ecd1d97 ("IB/core: Change wc.slid from 16 to 32 bits")
Signed-off-by: Bodong Wang <bodong@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/rdma/ib_verbs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -983,9 +983,9 @@ struct ib_wc {
u32 invalidate_rkey;
} ex;
u32 src_qp;
+ u32 slid;
int wc_flags;
u16 pkey_index;
- u32 slid;
u8 sl;
u8 dlid_path_bits;
u8 port_num; /* valid only for DR SMPs on switches */