mptcp: do not queue excessive data on subflows

The current packet scheduler can enqueue up to sndbuf data on each subflow. If the send buffer is large and the subflows are not symmetric, this could lead to suboptimal aggregate bandwidth utilization. Limit the amount of queued data to the maximum cwnd. Reviewed-by: Mat Martineau <[email protected]> Signed-off-by: Paolo Abeni <[email protected]>
multipath-tcp · Jan 14, 2021 · e61bdd4 · e61bdd4
1 parent 22a5014
commit e61bdd4
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
@@ -1390,7 +1390,7 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 			continue;
 
 		nr_active += !subflow->backup;
-		if (!sk_stream_memory_free(subflow->tcp_sock))
+		if (!sk_stream_memory_free(subflow->tcp_sock) || !tcp_sk(ssk)->snd_wnd)
 			continue;
 
 		pace = READ_ONCE(ssk->sk_pacing_rate);
@@ -1416,7 +1416,7 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 	if (send_info[0].ssk) {
 		msk->last_snd = send_info[0].ssk;
 		msk->snd_burst = min_t(int, MPTCP_SEND_BURST_SIZE,
-				       sk_stream_wspace(msk->last_snd));
+				       tcp_sk(msk->last_snd)->snd_wnd);
 		return msk->last_snd;
 	}