2020-07-06 12:45:57

by Matthieu Baerts

Subject: [PATCH net-next] selftests: mptcp: capture pcap on both sides

When investigating performance issues that involve latency / loss /
reordering it is useful to have the pcap from the sender-side as it
allows to easier infer the state of the sender's congestion-control,
loss-recovery, etc.

Allow the selftests to capture a pcap on both sender and receiver so
that this information is not lost when reproducing.

This patch also improves the file names. Instead of:

ns4-5ee79a56-X4O6gS-ns3-5ee79a56-X4O6gS-MPTCP-MPTCP-10.0.3.1.pcap

We now have something like for the same test:

5ee79a56-X4O6gS-ns3-ns4-MPTCP-MPTCP-10.0.3.1-10030-connector.pcap
5ee79a56-X4O6gS-ns3-ns4-MPTCP-MPTCP-10.0.3.1-10030-listener.pcap

It was a connection from ns3 to ns4, better to start with ns3 then. The
port is also added, easier to find the trace we want.

Co-developed-by: Christoph Paasch <[email protected]>
Signed-off-by: Christoph Paasch <[email protected]>
Signed-off-by: Matthieu Baerts <[email protected]>
---
tools/testing/selftests/net/mptcp/mptcp_connect.sh | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 8f7145c413b9..c0589e071f20 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -395,10 +395,14 @@ do_transfer()
capuser="-Z $SUDO_USER"
fi

- local capfile="${listener_ns}-${connector_ns}-${cl_proto}-${srv_proto}-${connect_addr}.pcap"
+ local capfile="${rndh}-${connector_ns:0:3}-${listener_ns:0:3}-${cl_proto}-${srv_proto}-${connect_addr}-${port}"
+ local capopt="-i any -s 65535 -B 32768 ${capuser}"

- ip netns exec ${listener_ns} tcpdump -i any -s 65535 -B 32768 $capuser -w $capfile > "$capout" 2>&1 &
- local cappid=$!
+ ip netns exec ${listener_ns} tcpdump ${capopt} -w "${capfile}-listener.pcap" >> "${capout}" 2>&1 &
+ local cappid_listener=$!
+
+ ip netns exec ${connector_ns} tcpdump ${capopt} -w "${capfile}-connector.pcap" >> "${capout}" 2>&1 &
+ local cappid_connector=$!

sleep 1
fi
@@ -423,7 +427,8 @@ do_transfer()

if $capture; then
sleep 1
- kill $cappid
+ kill ${cappid_listener}
+ kill ${cappid_connector}
fi

local duration
--
2.27.0

2020-07-06 19:48:18

by David Miller

Subject: Re: [PATCH net-next] selftests: mptcp: capture pcap on both sides

From: Matthieu Baerts <[email protected]>
Date: Mon, 6 Jul 2020 14:44:08 +0200

> When investigating performance issues that involve latency / loss /
> reordering it is useful to have the pcap from the sender-side as it
> allows to easier infer the state of the sender's congestion-control,
> loss-recovery, etc.
>
> Allow the selftests to capture a pcap on both sender and receiver so
> that this information is not lost when reproducing.
>
> This patch also improves the file names. Instead of:
>
> ns4-5ee79a56-X4O6gS-ns3-5ee79a56-X4O6gS-MPTCP-MPTCP-10.0.3.1.pcap
>
> We now have something like for the same test:
>
> 5ee79a56-X4O6gS-ns3-ns4-MPTCP-MPTCP-10.0.3.1-10030-connector.pcap
> 5ee79a56-X4O6gS-ns3-ns4-MPTCP-MPTCP-10.0.3.1-10030-listener.pcap
>
> It was a connection from ns3 to ns4, better to start with ns3 then. The
> port is also added, easier to find the trace we want.
>
> Co-developed-by: Christoph Paasch <[email protected]>
> Signed-off-by: Christoph Paasch <[email protected]>
> Signed-off-by: Matthieu Baerts <[email protected]>

Applied, thank you.