>From: Michael Qiu [mailto:[email protected]]
>Sent: Monday, June 19, 2017 6:29 AM
>To: [email protected]
>Cc: Kavanagh, Mark B <[email protected]>; [email protected];
>[email protected]; Michael Qiu <[email protected]>
>Subject: [PATCH 5/5] lib/netdev-dpdk: copy large packet to multi-segment mbufs
>
>From: Michael Qiu <[email protected]>
>
>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 <[email protected]>
Hi Michael,
One comment inline.
Thanks,
Mark
>---
> 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);
>
Need to check if rte_pktmbuf_alloc() succeeded here.
+
>+ /* 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) {
Could you please add a comment explaining in which scenario this section is
executed?
>From what I can tell, dpdk_do_tx_copy is invoked only from either
>netdev_dpdk_send__ and/or netdev_dpdk_vhost_send (as a result of the OUTPUT
>action) if one of the following two conditions are met:
1. the packet's 'source' != DPBUF_DPDK (N/A in this case)
2. 'may_steal' == false
The only case I've observed in which the output action is invoked and where
'may_steal' is false is in the context of dpif_execute; however, in this case,
I'm unsure if the packet's source is DPBUF_DPDK.
Thanks in advance.
>+ 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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