<div dir="ltr"><div>Please find the attached pcap files for the testing done. </div><div> </div><div>Thanks,</div><div>Kumara. </div></div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Oct 13, 2022 at 3:49 PM Kumara Parameshwaran <<a href="mailto:kumaraparamesh92@gmail.com">kumaraparamesh92@gmail.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">From: Kumara Parameshwaran <<a href="mailto:kumaraparamesh92@gmail.com" target="_blank">kumaraparamesh92@gmail.com</a>> When a TCP packet contains flags like PSH it is returned immediately to the application though there might be packets of the same flow in the GRO table. If PSH flag is set on a segment packets upto the segment should be delivered immediately. But the current implementation delivers the last arrived packet with PSH flag set causing re-ordering With this patch, if a packet does not contain only ACK flag and if there are no previous packets for the flow the packet would be returned immediately, else will be merged with the previous segment and the flag on the last segment will be set on the entire segment. This is the behaviour with linux stack as well Signed-off-by: Kumara Parameshwaran <<a href="mailto:kumaraparamesh92@gmail.com" target="_blank">kumaraparamesh92@gmail.com</a>> --- v1: If the received packet is not a pure ACK packet, we check if there are any previous packets in the flow, if present we indulge the received packet also in the coalescing logic and update the flags of the last recived packet to the entire segment which would avoid re-ordering. Lets say a case where P1(PSH), P2(ACK), P3(ACK) are received in burst mode, P1 contains PSH flag and since it does not contain any prior packets in the flow we copy it to unprocess_packets and P2(ACK) and P3(ACK) are merged together. In the existing case the P2,P3 would be delivered as single segment first and the unprocess_packets will be copied later which will cause reordering. With the patch copy the unprocess packets first and then the packets from the GRO table. Testing done The csum test-pmd was modifited to support the following GET request of 10MB from client to server via test-pmd (static arp entries added in client and server). Enable GRO and TSO in test-pmd where the packets recived from the client mac would be sent to server mac and vice versa. In above testing, without the patch the client observerd re-ordering of 25 packets and with the patch there were no packet re-ordering observerd. lib/gro/gro_tcp4.c | 35 ++++++++++++++++++++++++++++------- lib/gro/rte_gro.c | 18 +++++++++--------- 2 files changed, 37 insertions(+), 16 deletions(-) diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c index 8f5e800250..9ed891c253 100644 --- a/lib/gro/gro_tcp4.c +++ b/lib/gro/gro_tcp4.c @@ -188,6 +188,19 @@ update_header(struct gro_tcp4_item *item) pkt->l2_len); } +static inline void +update_tcp_hdr_flags(struct rte_tcp_hdr *tcp_hdr, struct rte_mbuf *pkt) +{ + struct rte_ether_hdr *eth_hdr; + struct rte_ipv4_hdr *ipv4_hdr; + struct rte_tcp_hdr *merged_tcp_hdr; + + eth_hdr = rte_pktmbuf_mtod(pkt, struct rte_ether_hdr *); + ipv4_hdr = (struct rte_ipv4_hdr *)((char *)eth_hdr + pkt->l2_len); + merged_tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len); + merged_tcp_hdr->tcp_flags |= tcp_hdr->tcp_flags; +} + int32_t gro_tcp4_reassemble(struct rte_mbuf *pkt, struct gro_tcp4_tbl *tbl, @@ -206,6 +219,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, uint32_t i, max_flow_num, remaining_flow_num; int cmp; uint8_t find; + uint32_t start_idx; /* * Don't process the packet whose TCP header length is greater @@ -219,12 +233,6 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len); hdr_len = pkt->l2_len + pkt->l3_len + pkt->l4_len; - /* - * Don't process the packet which has FIN, SYN, RST, PSH, URG, ECE - * or CWR set. - */ - if (tcp_hdr->tcp_flags != RTE_TCP_ACK_FLAG) - return -1; /* * Don't process the packet whose payload length is less than or * equal to 0. @@ -263,12 +271,21 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, if (tbl->flows[i].start_index != INVALID_ARRAY_INDEX) { if (is_same_tcp4_flow(tbl->flows[i].key, key)) { find = 1; + start_idx = tbl->flows[i].start_index; break; } remaining_flow_num--; } } + if (tcp_hdr->tcp_flags != RTE_TCP_ACK_FLAG) { + if (find) + /* Since PSH flag is set, start time will be set to 0 so it will be flushed immediately */ + tbl->items[start_idx].start_time = 0; + else + return -1; + } + /* * Fail to find a matched flow. Insert a new flow and store the * packet into the flow. @@ -303,8 +320,12 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, is_atomic); if (cmp) { if (merge_two_tcp4_packets(&(tbl->items[cur_idx]), - pkt, cmp, sent_seq, ip_id, 0)) + pkt, cmp, sent_seq, ip_id, 0)) { + if (tbl->items[cur_idx].start_time == 0) + update_tcp_hdr_flags(tcp_hdr, tbl->items[cur_idx].firstseg); return 1; + } + /* * Fail to merge the two packets, as the packet * length is greater than the max value. Store diff --git a/lib/gro/rte_gro.c b/lib/gro/rte_gro.c index e35399fd42..87c5502dce 100644 --- a/lib/gro/rte_gro.c +++ b/lib/gro/rte_gro.c @@ -283,10 +283,17 @@ rte_gro_reassemble_burst(struct rte_mbuf **pkts, if ((nb_after_gro < nb_pkts) || (unprocess_num < nb_pkts)) { i = 0; + /* Copy unprocessed packets */ + if (unprocess_num > 0) { + memcpy(&pkts[i], unprocess_pkts, + sizeof(struct rte_mbuf *) * + unprocess_num); + i = unprocess_num; + } /* Flush all packets from the tables */ if (do_vxlan_tcp_gro) { - i = gro_vxlan_tcp4_tbl_timeout_flush(&vxlan_tcp_tbl, - 0, pkts, nb_pkts); + i += gro_vxlan_tcp4_tbl_timeout_flush(&vxlan_tcp_tbl, + 0, &pkts[i], nb_pkts - i); } if (do_vxlan_udp_gro) { @@ -304,13 +311,6 @@ rte_gro_reassemble_burst(struct rte_mbuf **pkts, i += gro_udp4_tbl_timeout_flush(&udp_tbl, 0, &pkts[i], nb_pkts - i); } - /* Copy unprocessed packets */ - if (unprocess_num > 0) { - memcpy(&pkts[i], unprocess_pkts, - sizeof(struct rte_mbuf *) * - unprocess_num); - } - nb_after_gro = i + unprocess_num; } return nb_after_gro; -- 2.25.1 </blockquote></div>