> From: Thomas Monjalon [mailto:tho...@monjalon.net] > Sent: Monday, November 9, 2020 10:30 PM > > According to the Technical Board decision > (http://mails.dpdk.org/archives/dev/2020-November/191859.html), > the mempool pointer in the mbuf struct is moved > from the second to the first half. > It may increase performance in some cases > on systems having 64-byte cache line, i.e. mbuf split in two cache > lines. > > Due to this change, tx_offload is moved.
A minor correction: All fields after m->pool are moved up 8 bytes, not only m->tx_offload. > Hopefully no vector data path is impacted. > > Moving this field gives more space to dynfield1 > while dropping the temporary dynfield0. > > This is how the mbuf layout looks like (pahole-style): > > word type name byte size > 0 void * buf_addr; /* 0 + 8 > */ > 1 rte_iova_t buf_iova /* 8 + 8 > */ > /* --- RTE_MARKER64 rearm_data; > */ > 2 uint16_t data_off; /* 16 + 2 > */ > uint16_t refcnt; /* 18 + 2 > */ > uint16_t nb_segs; /* 20 + 2 > */ > uint16_t port; /* 22 + 2 > */ > 3 uint64_t ol_flags; /* 24 + 8 > */ > /* --- RTE_MARKER rx_descriptor_fields1; > */ > 4 uint32_t union packet_type; /* 32 + 4 > */ > uint32_t pkt_len; /* 36 + 4 > */ > 5 uint16_t data_len; /* 40 + 2 > */ > uint16_t vlan_tci; /* 42 + 2 > */ > 5.5 uint64_t union hash; /* 44 + 8 > */ > 6.5 uint16_t vlan_tci_outer; /* 52 + 2 > */ > uint16_t buf_len; /* 54 + 2 > */ > 7 struct rte_mempool * pool; /* 56 + 8 > */ > /* --- RTE_MARKER cacheline1; > */ > 8 struct rte_mbuf * next; /* 64 + 8 > */ > 9 uint64_t union tx_offload; /* 72 + 8 > */ > 10 struct rte_mbuf_ext_shared_info * shinfo; /* 80 + 8 > */ > 11 uint16_t priv_size; /* 88 + 2 > */ > uint16_t timesync; /* 90 + 2 > */ > 11.5 uint32_t dynfield1[9]; /* 92 + 36 > */ > 16 /* --- END 128 > */ > > Signed-off-by: Thomas Monjalon <tho...@monjalon.net> The minor detail doesn’t prevent... Acked-by: Morten Brørup <m...@smartsharesystems.com>
