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| author | Florian Westphal <fw@strlen.de> | 2020-06-30 21:24:45 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-01 17:47:55 -0700 |
| commit | a6b118febbab3f6454057612b355d0b667c1fafa (patch) | |
| tree | ccfd4936f10262e871a8707c7cf6b114a5da0e78 /net/mptcp/subflow.c | |
| parent | 767659f65000e6a19fee3b9bf6cda2839968329a (diff) | |
| download | linux-a6b118febbab3f6454057612b355d0b667c1fafa.tar.bz2 | |
mptcp: add receive buffer auto-tuning
When mptcp is used, userspace doesn't read from the tcp (subflow)
socket but from the parent (mptcp) socket receive queue.
skbs are moved from the subflow socket to the mptcp rx queue either from
'data_ready' callback (if mptcp socket can be locked), a work queue, or
the socket receive function.
This means tcp_rcv_space_adjust() is never called and thus no receive
buffer size auto-tuning is done.
An earlier (not merged) patch added tcp_rcv_space_adjust() calls to the
function that moves skbs from subflow to mptcp socket.
While this enabled autotuning, it also meant tuning was done even if
userspace was reading the mptcp socket very slowly.
This adds mptcp_rcv_space_adjust() and calls it after userspace has
read data from the mptcp socket rx queue.
Its very similar to tcp_rcv_space_adjust, with two differences:
1. The rtt estimate is the largest one observed on a subflow
2. The rcvbuf size and window clamp of all subflows is adjusted
to the mptcp-level rcvbuf.
Otherwise, we get spurious drops at tcp (subflow) socket level if
the skbs are not moved to the mptcp socket fast enough.
Before:
time mptcp_connect.sh -t -f $((4*1024*1024)) -d 300 -l 0.01% -r 0 -e "" -m mmap
[..]
ns4 MPTCP -> ns3 (10.0.3.2:10108 ) MPTCP (duration 40823ms) [ OK ]
ns4 MPTCP -> ns3 (10.0.3.2:10109 ) TCP (duration 23119ms) [ OK ]
ns4 TCP -> ns3 (10.0.3.2:10110 ) MPTCP (duration 5421ms) [ OK ]
ns4 MPTCP -> ns3 (dead:beef:3::2:10111) MPTCP (duration 41446ms) [ OK ]
ns4 MPTCP -> ns3 (dead:beef:3::2:10112) TCP (duration 23427ms) [ OK ]
ns4 TCP -> ns3 (dead:beef:3::2:10113) MPTCP (duration 5426ms) [ OK ]
Time: 1396 seconds
After:
ns4 MPTCP -> ns3 (10.0.3.2:10108 ) MPTCP (duration 5417ms) [ OK ]
ns4 MPTCP -> ns3 (10.0.3.2:10109 ) TCP (duration 5427ms) [ OK ]
ns4 TCP -> ns3 (10.0.3.2:10110 ) MPTCP (duration 5422ms) [ OK ]
ns4 MPTCP -> ns3 (dead:beef:3::2:10111) MPTCP (duration 5415ms) [ OK ]
ns4 MPTCP -> ns3 (dead:beef:3::2:10112) TCP (duration 5422ms) [ OK ]
ns4 TCP -> ns3 (dead:beef:3::2:10113) MPTCP (duration 5423ms) [ OK ]
Time: 296 seconds
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp/subflow.c')
| -rw-r--r-- | net/mptcp/subflow.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 664aa9158363..e1e19c76e267 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -225,8 +225,10 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) pr_fallback(mptcp_sk(subflow->conn)); } - if (mptcp_check_fallback(sk)) + if (mptcp_check_fallback(sk)) { + mptcp_rcv_space_init(mptcp_sk(parent), sk); return; + } if (subflow->mp_capable) { pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk), @@ -1118,6 +1120,7 @@ static void subflow_state_change(struct sock *sk) if (subflow_simultaneous_connect(sk)) { mptcp_do_fallback(sk); + mptcp_rcv_space_init(mptcp_sk(parent), sk); pr_fallback(mptcp_sk(parent)); subflow->conn_finished = 1; if (inet_sk_state_load(parent) == TCP_SYN_SENT) { |