From mboxrd@z Thu Jan  1 00:00:00 1970
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From: Paolo Abeni <pabeni at redhat.com>
To: mptcp at lists.01.org
Subject: [MPTCP] [PATCH mptcp-next 2/3] mptcp: do not queue excessive data on
 subflows.
Date: Fri, 08 Jan 2021 12:50:02 +0100
Message-ID: <e3849a616e06bdcb75fe64895c1b50532ce34546.1610106588.git.pabeni@redhat.com>
In-Reply-To: cover.1610106588.git.pabeni@redhat.com
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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.

Signed-off-by: Paolo Abeni <pabeni(a)redhat.com>
---
 net/mptcp/protocol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index eb6bb6b78d6f..b5b979671d92 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1414,7 +1414,7 @@ static struct sock *mptcp_subflow_get_send(struct mpt=
cp_sock *msk)
 			continue;
 =

 		nr_active +=3D !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 =3D READ_ONCE(ssk->sk_pacing_rate);
@@ -1441,7 +1441,7 @@ static struct sock *mptcp_subflow_get_send(struct mpt=
cp_sock *msk)
 	if (send_info[0].ssk) {
 		msk->last_snd =3D send_info[0].ssk;
 		msk->snd_burst =3D min_t(int, MPTCP_SEND_BURST_SIZE,
-				       sk_stream_wspace(msk->last_snd));
+				       tcp_sk(msk->last_snd)->snd_wnd);
 		return msk->last_snd;
 	}
 =

-- =

2.26.2

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