From: Hiroshi Shimamoto <h-shimam...@ct.jp.nec.com> To reduce instruction cache miss, add branch condition hints into recv/xmit functions. This improves a bit performance.
We can see performance improvements with memnic-tester. Using Xeon E5-2697 v2 @ 2.70GHz, 4 vCPU. size | before | after 64 | 5.54Mpps | 5.55Mpps 128 | 5.46Mpps | 5.44Mpps 256 | 5.21Mpps | 5.22Mpps 512 | 4.50Mpps | 4.52Mpps 1024 | 3.71Mpps | 3.73Mpps 1280 | 3.21Mpps | 3.22Mpps 1518 | 2.92Mpps | 2.93Mpps Signed-off-by: Hiroshi Shimamoto <h-shimamoto at ct.jp.nec.com> Reviewed-by: Hayato Momma <h-momma at ce.jp.nec.com> --- pmd/pmd_memnic.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/pmd/pmd_memnic.c b/pmd/pmd_memnic.c index 7fc3093..875d3ea 100644 --- a/pmd/pmd_memnic.c +++ b/pmd/pmd_memnic.c @@ -289,26 +289,26 @@ static uint16_t memnic_recv_pkts(void *rx_queue, int idx, next; struct rte_eth_stats *st = &adapter->stats[rte_lcore_id()]; - if (!adapter->nic->hdr.valid) + if (unlikely(!adapter->nic->hdr.valid)) return 0; pkts = bytes = errs = 0; idx = adapter->up_idx; for (nr = 0; nr < nb_pkts; nr++) { p = &data->packets[idx]; - if (p->status != MEMNIC_PKT_ST_FILLED) + if (unlikely(p->status != MEMNIC_PKT_ST_FILLED)) break; /* prefetch the next area */ next = idx; - if (++next >= MEMNIC_NR_PACKET) + if (unlikely(++next >= MEMNIC_NR_PACKET)) next = 0; rte_prefetch0(&data->packets[next]); - if (p->len > framesz) { + if (unlikely(p->len > framesz)) { errs++; goto drop; } mb = rte_pktmbuf_alloc(adapter->mp); - if (!mb) + if (unlikely(!mb)) break; rte_memcpy(rte_pktmbuf_mtod(mb, void *), p->data, p->len); @@ -350,7 +350,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue, uint64_t pkts, bytes, errs; uint32_t framesz = adapter->framesz; - if (!adapter->nic->hdr.valid) + if (unlikely(!adapter->nic->hdr.valid)) return 0; pkts = bytes = errs = 0; @@ -360,7 +360,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue, struct rte_mbuf *sg; void *ptr; - if (pkt_len > framesz) { + if (unlikely(pkt_len > framesz)) { errs++; break; } @@ -379,7 +379,7 @@ retry: goto retry; } - if (idx != ACCESS_ONCE(adapter->down_idx)) { + if (unlikely(idx != ACCESS_ONCE(adapter->down_idx))) { /* * host freed this and got false positive, * need to recover the status and retry. @@ -388,7 +388,7 @@ retry: goto retry; } - if (++idx >= MEMNIC_NR_PACKET) + if (unlikely(++idx >= MEMNIC_NR_PACKET)) idx = 0; adapter->down_idx = idx; -- 1.8.3.1