[dpdk-dev] [RFC 0/8] mbuf: structure reorganization

[Chilikin, Andrey]

While doing this fields reshuffling,  any chance to put uint16_t vlan_tci_outer beside uint16_t vlan_tci? It will allow to treat QinQ tags as a single 32-bit tag, if needed, and use it for other tag/labels like MPLS, GRE, NSH which could be 20, 24, 32 bits wide.

/Andrey

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier Matz
> Sent: Tuesday, January 24, 2017 3:19 PM
> To: dev at dpdk.org
> Subject: [dpdk-dev] [RFC 0/8] mbuf: structure reorganization
> 
> Based on discussion done in [1], this patchset reorganizes the mbuf.
> 
> The main changes are:
> - reorder structure to increase vector performance on some non-ia
>   platforms.
> - add a 64bits timestamp field in the 1st cache line
> - m->next, m->nb_segs, and m->refcnt are always initialized for mbufs
>   in the pool, avoiding the need of setting m->next (located in the
>   2nd cache line) in the Rx path for mono-segment packets.
> - change port and nb_segs to 16 bits
> - move seqn in the 2nd cache line
> 
> Things discussed but not done in the patchset:
> - move refcnt and nb_segs to the 2nd cache line: many drivers sets
>   them in the Rx path, so it could introduce a performance regression, or
>   it would require to change all the drivers, which is not an easy task.
> - remove the m->port field: too much impact on many examples and
> libraries,
>   and some people highlighted they are using it.
> - moving m->next in the 1st cache line: there is not enough room, and having
>   it set to NULL for unused mbuf should remove the need for it.
> - merge seqn and timestamp together in a union: we could imagine use cases
>   were both are activated. There is no flag indicating the presence of seqn,
>   so it looks preferable to keep them separated for now.
> 
> I made some basic performance tests (ixgbe) and see no regression, but the
> patchset requires more testing.
> 
> [1] http://dpdk.org/ml/archives/dev/2016-October/049338.html
> 
> 
> Jerin Jacob (1):
>   mbuf: make rearm data address naturally aligned
> 
> Olivier Matz (7):
>   mbuf: make segment prefree function public
>   mbuf: make raw free function public
>   mbuf: set mbuf fields while in pool
>   net: don't touch mbuf next or nb segs on Rx
>   mbuf: use 2 bytes for port and nb segments
>   mbuf: move sequence number in second cache line
>   mbuf: add a timestamp field
> 
>  app/test-pmd/csumonly.c                            |   4 +-
>  drivers/net/ena/ena_ethdev.c                       |   2 +-
>  drivers/net/enic/enic_rxtx.c                       |   2 +-
>  drivers/net/fm10k/fm10k_rxtx.c                     |   6 +-
>  drivers/net/fm10k/fm10k_rxtx_vec.c                 |   9 +-
>  drivers/net/i40e/i40e_rxtx_vec_common.h            |   6 +-
>  drivers/net/i40e/i40e_rxtx_vec_sse.c               |  11 +-
>  drivers/net/ixgbe/ixgbe_rxtx.c                     |  10 +-
>  drivers/net/ixgbe/ixgbe_rxtx_vec_common.h          |   6 +-
>  drivers/net/ixgbe/ixgbe_rxtx_vec_neon.c            |   9 --
>  drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c             |   9 --
>  drivers/net/mlx5/mlx5_rxtx.c                       |  11 +-
>  drivers/net/mpipe/mpipe_tilegx.c                   |   3 +-
>  drivers/net/null/rte_eth_null.c                    |   2 -
>  drivers/net/virtio/virtio_rxtx.c                   |   3 -
>  drivers/net/virtio/virtio_rxtx_simple.h            |   6 +-
>  .../linuxapp/eal/include/exec-env/rte_kni_common.h |   5 +-
>  lib/librte_mbuf/rte_mbuf.c                         |   4 +
>  lib/librte_mbuf/rte_mbuf.h                         | 114 ++++++++++++++++-----
>  19 files changed, 124 insertions(+), 98 deletions(-)
> 
> --
> 2.8.1