[dpdk-dev] [PATCH v2 2/2] mbuf: move pool pointer in first half
Thomas Monjalon
thomas at monjalon.net
Thu Nov 12 15:39:27 CET 2020
> > > 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.
> > > 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 <thomas at monjalon.net>
> >
> > Acked-by: Olivier Matz <olivier.matz at 6wind.com>
>
> Acked-by: Jerin Jacob <jerinj at marvell.com>
Series applied
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