Commit 5264ab61 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by Jakub Kicinski
Browse files

selftests/net: calibrate txtimestamp 



The test sends packets and compares enqueue, transmit and Ack
timestamps with expected values. It installs netem delays to increase
latency between these points.

The test proves flaky in virtual environment (vng). Increase the
delays to reduce variance. Scale measurement tolerance accordingly.

Time sensitive tests are difficult to calibrate. Increasing delays 10x
also increases runtime 10x, for one. And it may still prove flaky at
some rate.

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240127023212.3746239-1-willemdebruijn.kernel@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 84fc2408

tools/testing/selftests/net/txtimestamp.sh

+7 −5
Original line number Diff line number Diff line
@@ -8,13 +8,13 @@ set -e 


setup() {

	# set 1ms delay on lo egress

	tc qdisc add dev lo root netem delay 1ms

	tc qdisc add dev lo root netem delay 10ms



	# set 2ms delay on ifb0 egress

	modprobe ifb

	ip link add ifb_netem0 type ifb

	ip link set dev ifb_netem0 up

	tc qdisc add dev ifb_netem0 root netem delay 2ms

	tc qdisc add dev ifb_netem0 root netem delay 20ms



	# redirect lo ingress through ifb0 egress

	tc qdisc add dev lo handle ffff: ingress
@@ -24,9 +24,11 @@ setup() { 
}



run_test_v4v6() {

	# SND will be delayed 1000us

	# ACK will be delayed 6000us: 1 + 2 ms round-trip

	local -r args="$@ -v 1000 -V 6000"

	# SND will be delayed 10ms

	# ACK will be delayed 60ms: 10 + 20 ms round-trip

	# allow +/- tolerance of 8ms

	# wait for ACK to be queued

	local -r args="$@ -v 10000 -V 60000 -t 8000 -S 80000"



	./txtimestamp ${args} -4 -L 127.0.0.1

	./txtimestamp ${args} -6 -L ::1