Hi Olivier I'm wondering why rte_pktmbuf_prefree_seg() checks m->next instead of m->nb_segs? As 'next' is in the 2nd cacheline, checking nb_segs seems beneficial to the cases where almost mbufs have single segment.
A customer reported high rate of cache misses in the code and I thought the following patch could be helpful. I haven't had them try it yet but just wanted to hear from you. I'd appreciate if you can review this idea. diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h index 62740254d..96edbcb9e 100644 --- a/lib/librte_mbuf/rte_mbuf.h +++ b/lib/librte_mbuf/rte_mbuf.h @@ -1398,7 +1398,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) if (RTE_MBUF_INDIRECT(m)) rte_pktmbuf_detach(m); - if (m->next != NULL) { + if (m->nb_segs > 1) { m->next = NULL; m->nb_segs = 1; } @@ -1410,7 +1410,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) if (RTE_MBUF_INDIRECT(m)) rte_pktmbuf_detach(m); - if (m->next != NULL) { + if (m->nb_segs > 1) { m->next = NULL; m->nb_segs = 1; } Thanks, Yongseok