[ovs-dev] [PATCH 5/5] lib/netdev-dpdk: copy large packet to multi-segment mbufs

Michael Qiu qdy220091330 at gmail.com
Mon Jun 19 05:29:03 UTC 2017


From: Michael Qiu <qiudayu at chinac.com>

Currently, one packet is only copied to one segment
in function dpdk_do_tx_copy(),  this could be an issue
when a jumbo frame comes, especially for multiple segments.

This patch calculate the segment number needed by the packet and
copy the data to different segments.

Signed-off-by: Michael Qiu <qiudayu at chinac.com>
---
 lib/netdev-dpdk.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 0485872..38ec2ed 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -1776,14 +1776,16 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
 #endif
     struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
     struct rte_mbuf *pkts[PKT_ARRAY_SIZE];
+    struct rte_mbuf *temp, *head = NULL;
     int dropped = 0;
     int newcnt = 0;
-    int i;
+    int i, j, nb_segs;
 
     dp_packet_batch_apply_cutlen(batch);
 
     for (i = 0; i < batch->count; i++) {
         int size = dp_packet_size(batch->packets[i]);
+        int max_data_len, tmp_len;
 
         if (OVS_UNLIKELY(size > dev->max_packet_len)) {
             VLOG_WARN_RL(&rl, "Too big size %d max_packet_len %d",
@@ -1793,7 +1795,24 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
             continue;
         }
 
-        pkts[newcnt] = rte_pktmbuf_alloc(dev->dpdk_mp->mp);
+        temp = pkts[newcnt] = rte_pktmbuf_alloc(dev->dpdk_mp->mp);
+
+        /* all new allocated mbuf's max data len is the same */
+        max_data_len = temp->buf_len - temp->data_off;
+
+        nb_segs = size/max_data_len;
+        if (size % max_data_len)
+            nb_segs = nb_segs + 1;
+
+        for (j = 1; j < nb_segs; j++) {
+            temp->next = rte_pktmbuf_alloc(dev->dpdk_mp->mp);
+            if (!temp->next) {
+                rte_pktmbuf_free(pkts[newcnt]);
+                pkts[newcnt] = NULL;
+                break;
+            }
+            temp = temp->next;
+        }
 
         if (!pkts[newcnt]) {
             dropped += batch->count - i;
@@ -1801,10 +1820,34 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch)
         }
 
         /* We have to do a copy for now */
-        memcpy(rte_pktmbuf_mtod(pkts[newcnt], void *),
-               dp_packet_data(batch->packets[i]), size);
+        rte_pktmbuf_pkt_len(pkts[newcnt]) = size;
+        temp = pkts[newcnt];
+        tmp_len = size < max_data_len ? size: max_data_len;
+        if (batch->packets[i]->source == DPBUF_DPDK) {
+            head = &(batch->packets[i]->mbuf);
+            while (temp && head && size > 0) {
+                rte_memcpy(rte_pktmbuf_mtod(temp, void*), dp_packet_data((struct dp_packet *)head),tmp_len);
+                rte_pktmbuf_data_len(temp) = tmp_len;
+                head = head->next;
+                size = size - tmp_len;
+                tmp_len =  size < max_data_len ? size: max_data_len;
+                temp = temp->next;
+            }
+        } else {
+            int offset = 0;
+            while (temp && size > 0) {
+                memcpy(rte_pktmbuf_mtod(temp, void *),
+                    dp_packet_at(batch->packets[i], offset,tmp_len), tmp_len);
+                rte_pktmbuf_data_len(temp) = tmp_len;
+                temp = temp->next;
+                size = size - tmp_len;
+                offset +=tmp_len;
+                tmp_len =  size < max_data_len ? size: max_data_len;
+            }
+        }
+
 
-        pkts[newcnt]->nb_segs = batch->packets[i]->mbuf.nb_segs;
+        pkts[newcnt]->nb_segs = nb_segs;
         pkts[newcnt]->ol_flags = batch->packets[i]->mbuf.ol_flags;
         pkts[newcnt]->packet_type = batch->packets[i]->mbuf.packet_type;
         pkts[newcnt]->tx_offload = batch->packets[i]->mbuf.tx_offload;
-- 
1.8.3.1



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