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* [dpdk-dev] ixgbe: prefetch packet headers in vector PMD receive function
@ 2015-09-01 19:17 Zoltan Kiss
  2015-09-07 12:25 ` [dpdk-dev] [PATCH] " Zoltan Kiss
  0 siblings, 1 reply; 14+ messages in thread
From: Zoltan Kiss @ 2015-09-01 19:17 UTC (permalink / raw)
  To: dev

The lack of this prefetch causes a significant performance drop in
OVS-DPDK: 13.3 Mpps instead of 14 when forwarding 64 byte packets. Even
though OVS prefetches the next packet's header before it starts processing
the current one, it doesn't get there fast enough. This aligns with the
behaviour of other receive functions.

Signed-off-by: Zoltan Kiss <zoltan.kiss@linaro.org>
---
diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec.c b/drivers/net/ixgbe/ixgbe_rxtx_vec.c
index cf25a53..51299fa 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec.c
@@ -502,6 +502,15 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
                _mm_storeu_si128((void *)&rx_pkts[pos]->rx_descriptor_fields1,
                                pkt_mb1);
 
+               rte_packet_prefetch((char*)(rx_pkts[pos]->buf_addr) +
+                                   RTE_PKTMBUF_HEADROOM);
+               rte_packet_prefetch((char*)(rx_pkts[pos + 1]->buf_addr) +
+                                   RTE_PKTMBUF_HEADROOM);
+               rte_packet_prefetch((char*)(rx_pkts[pos + 2]->buf_addr) +
+                                   RTE_PKTMBUF_HEADROOM);
+               rte_packet_prefetch((char*)(rx_pkts[pos + 3]->buf_addr) +
+                                   RTE_PKTMBUF_HEADROOM);
+
                /* C.4 calc avaialbe number of desc */
                var = __builtin_popcountll(_mm_cvtsi128_si64(staterr));
                nb_pkts_recd += var;

^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2015-10-20  9:58 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-09-01 19:17 [dpdk-dev] ixgbe: prefetch packet headers in vector PMD receive function Zoltan Kiss
2015-09-07 12:25 ` [dpdk-dev] [PATCH] " Zoltan Kiss
2015-09-07 12:57   ` Richardson, Bruce
2015-09-07 14:15     ` Zoltan Kiss
2015-09-07 14:41       ` Richardson, Bruce
2015-09-25 18:28         ` Zoltan Kiss
2015-09-27 23:19           ` Ananyev, Konstantin
2015-10-14 16:10             ` Zoltan Kiss
2015-10-14 23:23               ` Ananyev, Konstantin
2015-10-15 10:32                 ` Zoltan Kiss
2015-10-15 15:43                   ` Ananyev, Konstantin
2015-10-19 16:30                     ` Zoltan Kiss
2015-10-19 18:57                       ` Ananyev, Konstantin
2015-10-20  9:58                         ` Zoltan Kiss

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