[dpdk-dev] [PATCH 7/8] app/testpmd: don't use tso if packet is too small

[Olivier Matz <olivier.matz@6wind.com>]

Asking for TSO (TCP Segmentation Offload) on packets that are already
smaller than (headers + MSS) does not work, for instance on ixgbe.

Fix the csumonly engine to only set the TSO flag when a segmentation
offload is really required, i.e. when packet is large enough.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 app/test-pmd/csumonly.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index 35edf1d..9938150 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -102,6 +102,7 @@ struct testpmd_offload_info {
 	uint16_t outer_l3_len;
 	uint8_t outer_l4_proto;
 	uint16_t tso_segsz;
+	uint32_t pkt_len;
 };
 
 /* simplified GRE header */
@@ -329,13 +330,20 @@ process_inner_cksums(void *l3_hdr, const struct testpmd_offload_info *info,
 	struct tcp_hdr *tcp_hdr;
 	struct sctp_hdr *sctp_hdr;
 	uint64_t ol_flags = 0;
+	uint32_t max_pkt_len, tso_segsz = 0;
+
+	/* ensure packet is large enough to require tso */
+	max_pkt_len = info->l2_len + info->l3_len + info->l4_len +
+		info->tso_segsz;
+	if (info->tso_segsz != 0 && info->pkt_len > max_pkt_len)
+		tso_segsz = info->tso_segsz;
 
 	if (info->ethertype == _htons(ETHER_TYPE_IPv4)) {
 		ipv4_hdr = l3_hdr;
 		ipv4_hdr->hdr_checksum = 0;
 
 		ol_flags |= PKT_TX_IPV4;
-		if (info->tso_segsz != 0 && info->l4_proto == IPPROTO_TCP) {
+		if (tso_segsz != 0 && info->l4_proto == IPPROTO_TCP) {
 			ol_flags |= PKT_TX_IP_CKSUM;
 		} else {
 			if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM)
@@ -367,7 +375,7 @@ process_inner_cksums(void *l3_hdr, const struct testpmd_offload_info *info,
 	} else if (info->l4_proto == IPPROTO_TCP) {
 		tcp_hdr = (struct tcp_hdr *)((char *)l3_hdr + info->l3_len);
 		tcp_hdr->cksum = 0;
-		if (info->tso_segsz != 0) {
+		if (tso_segsz != 0) {
 			ol_flags |= PKT_TX_TCP_SEG;
 			tcp_hdr->cksum = get_psd_sum(l3_hdr, info->ethertype,
 				ol_flags);
@@ -667,6 +675,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
 
 		m = pkts_burst[i];
 		info.is_tunnel = 0;
+		info.pkt_len = rte_pktmbuf_pkt_len(m);
 		tx_ol_flags = 0;
 		rx_ol_flags = m->ol_flags;
 
-- 
2.8.1