gedit kernel/net/mptcp/mptcp_output.c
bool mptcp_write_xmit(struct sock *meta_sk, unsigned int mss_now, int nonagle,
int push_one, gfp_t gfp)
{
struct tcp_sock *meta_tp = tcp_sk(meta_sk), *subtp;
struct sock *subsk = NULL;
struct mptcp_cb *mpcb = meta_tp->mpcb;
struct sk_buff *skb;
int reinject = 0;
unsigned int sublimit;
__u32 path_mask = 0;
//ztg add
printk(KERN_INFO "mptcp: mptcp_write_xmit: 1111
");
while ((skb = mpcb->sched_ops->next_segment(meta_sk, &reinject, &subsk,
&sublimit))) {
unsigned int limit;
WARN(TCP_SKB_CB(skb)->sacked, "sacked: %u reinject: %u",
TCP_SKB_CB(skb)->sacked, reinject);
//ztg add
printk(KERN_INFO "mptcp: mptcp_write_xmit: 2222
");
subtp = tcp_sk(subsk);
mss_now = tcp_current_mss(subsk);
if (reinject == 1) {
if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una)) {
/* Segment already reached the peer, take the next one */
__skb_unlink(skb, &mpcb->reinject_queue);
__kfree_skb(skb);
continue;
}
}
/* If the segment was cloned (e.g. a meta retransmission),
* the header must be expanded/copied so that there is no
* corruption of TSO information.
*/
if (skb_unclone(skb, GFP_ATOMIC))
break;
if (unlikely(!tcp_snd_wnd_test(meta_tp, skb, mss_now)))
break;
/* Force tso_segs to 1 by using UINT_MAX.
* We actually don't care about the exact number of segments
* emitted on the subflow. We need just to set tso_segs, because
* we still need an accurate packets_out count in
* tcp_event_new_data_sent.
*/
tcp_set_skb_tso_segs(skb, UINT_MAX);
/* Check for nagle, irregardless of tso_segs. If the segment is
* actually larger than mss_now (TSO segment), then
* tcp_nagle_check will have partial == false and always trigger
* the transmission.
* tcp_write_xmit has a TSO-level nagle check which is not
* subject to the MPTCP-level. It is based on the properties of
* the subflow, not the MPTCP-level.
*/
if (unlikely(!tcp_nagle_test(meta_tp, skb, mss_now,
(tcp_skb_is_last(meta_sk, skb) ?
nonagle : TCP_NAGLE_PUSH))))
break;
limit = mss_now;
/* skb->len > mss_now is the equivalent of tso_segs > 1 in
* tcp_write_xmit. Otherwise split-point would return 0.
*/
if (skb->len > mss_now && !tcp_urg_mode(meta_tp))
/* We limit the size of the skb so that it fits into the
* window. Call tcp_mss_split_point to avoid duplicating
* code.
* We really only care about fitting the skb into the
* window. That's why we use UINT_MAX. If the skb does
* not fit into the cwnd_quota or the NIC's max-segs
* limitation, it will be split by the subflow's
* tcp_write_xmit which does the appropriate call to
* tcp_mss_split_point.
*/
limit = tcp_mss_split_point(meta_sk, skb, mss_now,
UINT_MAX / mss_now,
nonagle);
if (sublimit)
limit = min(limit, sublimit);
if (skb->len > limit &&
unlikely(mptcp_fragment(meta_sk, skb, limit, gfp, reinject)))
break;
if (!mptcp_skb_entail(subsk, skb, reinject))
break;
/* Nagle is handled at the MPTCP-layer, so
* always push on the subflow
*/
__tcp_push_pending_frames(subsk, mss_now, TCP_NAGLE_PUSH);
meta_tp->lsndtime = tcp_time_stamp;
//ztg add
printk(KERN_INFO "mptcp: mptcp_write_xmit: 3333
");
path_mask |= mptcp_pi_to_flag(subtp->mptcp->path_index);
skb_mstamp_get(&skb->skb_mstamp);
if (!reinject) {
mptcp_check_sndseq_wrap(meta_tp,
TCP_SKB_CB(skb)->end_seq -
TCP_SKB_CB(skb)->seq);
tcp_event_new_data_sent(meta_sk, skb);
}
tcp_minshall_update(meta_tp, mss_now, skb);
if (reinject > 0) {
__skb_unlink(skb, &mpcb->reinject_queue);
kfree_skb(skb);
}
if (push_one)
break;
}
mptcp_for_each_sk(mpcb, subsk) {
subtp = tcp_sk(subsk);
//ztg add
//----------------------------------------------------------------------
printk(KERN_INFO "mptcp: mptcp_write_xmit: 4444
");
printk(KERN_INFO "mptcp: mptcp_write_xmit: src_addr:%pI4:%d dst_addr:%pI4:%d, cnt_subflows now %d
",
&((struct inet_sock *)tcp_sk(subsk))->inet_saddr,
ntohs(((struct inet_sock *)tcp_sk(subsk))->inet_sport),
&((struct inet_sock *)tcp_sk(subsk))->inet_daddr,
ntohs(((struct inet_sock *)tcp_sk(subsk))->inet_dport),
tcp_sk(meta_sk)->mpcb->cnt_subflows);
//----------------------------------------------------------------------
if (!(path_mask & mptcp_pi_to_flag(subtp->mptcp->path_index)))
continue;
/* We have pushed data on this subflow. We ignore the call to
* cwnd_validate in tcp_write_xmit as is_cwnd_limited will never
* be true (we never push more than what the cwnd can accept).
* We need to ensure that we call tcp_cwnd_validate with
* is_cwnd_limited set to true if we have filled the cwnd.
*/
tcp_cwnd_validate(subsk, tcp_packets_in_flight(subtp) >=
subtp->snd_cwnd);
}
return !meta_tp->packets_out && tcp_send_head(meta_sk);
}===========================================================================================================================
四种测试情况，具体结果 看下图
==========================================
# eth0, eth1
# "Default" "Round-Robin" "Redundant"
# 流量均衡走 eth0 & eth1, 不能够完整的传输文件 (缺少 +300 Bytes)，mptcp_write_xmit() 被调用 1 次
# eth0, eth1
# "Round-Robin" "Redundant" "Default"
# 流量均衡走 eth0 & eth1, 不能够完整的传输文件 (缺少 +300 Bytes)，mptcp_write_xmit() 被调用 1 次
# eth0, eth1, eth2 (dhcp)
# "Default" "Round-Robin" "Redundant"
# 流量主要走 eth2 (dhcp), 能够完整的传输文件，mptcp_write_xmit() 被调用 1 次
# eth0, eth1, eth2 (dhcp)
# "Round-Robin" "Redundant" "Default"
# 流量主要走 eth2 (dhcp), 能够完整的传输文件，mptcp_write_xmit() 被调用 5 次 或 3 次 (每次测试，调用的次数不一样)
===========================================================================================================================
# eth0, eth1
# "Default" "Round-Robin" "Redundant"
# 流量均衡走 eth0 & eth1, 不能够完整的传输文件 (缺少 +300 Bytes)，mptcp_write_xmit() 被调用 1 次
更详细的输出
===========================================================================================================================
# eth0, eth1
# "Round-Robin" "Redundant" "Default"# 流量均衡走 eth0 & eth1, 不能够完整的传输文件 (缺少 +300 Bytes)，mptcp_write_xmit() 被调用 1 次
===========================================================================================================================
# "Default" "Round-Robin" "Redundant"
# 流量主要走 eth2 (dhcp), 能够完整的传输文件，mptcp_write_xmit() 被调用 1 次
===========================================================================================================================
# eth0, eth1, eth2 (dhcp)
# "Round-Robin" "Redundant" "Default"# 流量主要走 eth2 (dhcp), 能够完整的传输文件，mptcp_write_xmit() 被调用 5 次
