Based on discussions done in [1] and in this thread, 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. This timestamp is not normalized, i.e. no unit or time reference is enforced. A library may be added to do this job in the future. - 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. Other tests from NIC vendors are welcome. Once this patchset is pushed, the Rx path of drivers could be optimized a bit, by removing writes to m->next, m->nb_segs and m->refcnt. The patch 4/8 gives an idea of what could be done. [1] http://dpdk.org/ml/archives/dev/2016-October/049338.html rfc->v1: - fix reset of mbuf fields in case of indirect mbuf in rte_pktmbuf_prefree_seg() - do not enforce a unit or time reference for m->timestamp - reorganize fields to make vlan and outer vlan consecutive - enhance documentation of m->refcnt and m->port to explain why they are 16bits Jerin Jacob (1): mbuf: make rearm data address naturally aligned Olivier Matz (8): mbuf: make segment prefree function public mbuf: make raw free function public mbuf: set mbuf fields while in pool drivers/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 mbuf: reorder VLAN tci and buffer len fields 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 | 4 - 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 | 123 ++++++++++++++++----- 19 files changed, 130 insertions(+), 102 deletions(-) -- 2.8.1
