The 'next' and 'nb_segs' fields are already reset on newly allocated reinitialized mbufs (a.k.a. raw mbufs), so a simpler reset function for reinitialized mbufs was added.
The 'ol_flags' field must indicate whether the mbuf uses an external buffer. Unlike the normal packet mbuf reset function, which gets this information from the mbuf itself (by masking the RTE_MBUF_F_EXTERNAL flag), the simpler reset function gets this information from the mempool, thereby reducing the number of read-modify-writes on the mbuf from two to one. The remaining read-modify-write on the mbuf in the simpler reset function is in rte_pktmbuf_reset_headroom(), where the 'buf_len' field is read before writing the 'data_off' field. And I am hoping that it will be possible to eliminate that one too. Signed-off-by: Morten Brørup <[email protected]> --- lib/mbuf/rte_mbuf.h | 43 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-) diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h index 49c93ab356..92a1e8ba7e 100644 --- a/lib/mbuf/rte_mbuf.h +++ b/lib/mbuf/rte_mbuf.h @@ -954,6 +954,39 @@ static inline void rte_pktmbuf_reset_headroom(struct rte_mbuf *m) (uint16_t)m->buf_len); } +/** + * Reset the fields of a packet mbuf to their default values. + * + * The caller must ensure that the mbuf comes from the specified mempool, + * is direct and properly reinitialized (refcnt=1, next=NULL, nb_segs=1), + * as done by rte_pktmbuf_prefree_seg(). + * + * This function should be used with care, when optimization is required. + * For standard needs, prefer rte_pktmbuf_reset(). + * + * @param mp + * The mempool to which the mbuf belongs. + * @param m + * The packet mbuf to be reset. + */ +static inline void rte_mbuf_raw_reset(struct rte_mempool *mp, struct rte_mbuf *m) +{ + uint32_t flags = rte_pktmbuf_priv_flags(mp); + + m->pkt_len = 0; + m->tx_offload = 0; + m->vlan_tci = 0; + m->vlan_tci_outer = 0; + m->port = RTE_MBUF_PORT_INVALID; + + m->ol_flags = (flags & RTE_PKTMBUF_POOL_F_PINNED_EXT_BUF) ? RTE_MBUF_F_EXTERNAL : 0; + m->packet_type = 0; + rte_pktmbuf_reset_headroom(m); + + m->data_len = 0; + __rte_mbuf_sanity_check(m, 1); +} + /** * Reset the fields of a packet mbuf to their default values. * @@ -997,7 +1030,7 @@ static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp) { struct rte_mbuf *m; if ((m = rte_mbuf_raw_alloc(mp)) != NULL) - rte_pktmbuf_reset(m); + rte_mbuf_raw_reset(mp, m); return m; } @@ -1033,19 +1066,19 @@ static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool, switch (count % 4) { case 0: while (idx != count) { - rte_pktmbuf_reset(mbufs[idx]); + rte_mbuf_raw_reset(pool, mbufs[idx]); idx++; /* fall-through */ case 3: - rte_pktmbuf_reset(mbufs[idx]); + rte_mbuf_raw_reset(pool, mbufs[idx]); idx++; /* fall-through */ case 2: - rte_pktmbuf_reset(mbufs[idx]); + rte_mbuf_raw_reset(pool, mbufs[idx]); idx++; /* fall-through */ case 1: - rte_pktmbuf_reset(mbufs[idx]); + rte_mbuf_raw_reset(pool, mbufs[idx]); idx++; /* fall-through */ } -- 2.43.0
