Packet size can make a big difference to UDP throughput, so it makes sense
to measure it for a variety of different sizes.  Currently we do this by
adjusting the MTU on the relevant interface before running iperf3.

However, the UDP packet size has no inherent connection to the MTU - it's
controlled by the sender, and the MTU just affects whether the packet will
make it through or be fragmented.  The only reason adjusting the MTU works
is because iperf3 bases its default packet size on the (path) MTU.

We can test this more simply by using the -l option to the iperf3 client
to directly control the packet size, instead of adjusting the MTU.

As well as simplifying this lets us test different packet sizes for host to
ns traffic.  We couldn't do that previously because we don't have
permission to change the MTU on the host.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Currently we start both the iperf3 server(s) and client(s) afresh each time
we want to make a bandwidth measurement.  That's not really necessary as
usually a whole batch of bandwidth measurements can use the same server.

Split up the iperf3 directive into 3 directives: iperf3s to start the
server, iperf3 to make a measurement and iperf3k to kill the server, so
that we can start the server less often.  This - and more importantly, the
reduced number of waits for the server to be ready - reduces runtime of the
performance tests on my laptop by about 4m (out of ~28minutes).

For now we still restart the server between IPv4 and IPv6 tests.  That's
because in some cases the latency measurements we make in between use the
same ports.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

In practical terms, passt doesn't benefit from the additional
protection offered by the AGPL over the GPL, because it's not
suitable to be executed over a computer network.

Further, restricting the distribution under the version 3 of the GPL
wouldn't provide any practical advantage either, as long as the passt
codebase is concerned, and might cause unnecessary compatibility
dilemmas.

Change licensing terms to the GNU General Public License Version 2,
or any later version, with written permission from all current and
past contributors, namely: myself, David Gibson, Laine Stump, Andrea
Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian
Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Now that we require 13c6be96618c ("net: stream: add unix socket")
in qemu to run the tests, we can also assume that commit df8d07081718
("virtio-net: fix bottom-half packet TX on asynchronous completion")
is present, as it was merged before that one.

This fixes the issue we attempted to work around in passt TCP and
UDP performance tests: finally drop that stuff.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Starting tcp_rr, tcp_crr, udp_rr servers in the guest takes a bit
longer than starting the corresponding clients on the host, and we
end up starting clients before servers unless we add a delay there.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

It appears that if we run throughput tests with one-second periodic
reports, the sending side of the vhost channel used for SSH-based
command dispatch occasionally stops working altogether. I haven't
investigated this further, all I see is that output is truncated
at some point, and doesn't resume.

If we use gzip compression (ssh -C) this happens less frequently,
but it still happens, seemingly indicating the issue is probably
related to vhost itself.

Disable periodic reports in iperf3 clients. The -i options were
actually redundant, so remove them from both test files as well as
from test_iperf3().

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

It looks like the workaround for the virtio_net TX hang issue is
working less reliably with the new command dispatch mechanism, I'm
not sure why. Switch to 10 seconds, at least for the moment.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Otherwise, we're depending on having /sbin in $PATH. For some reason
I didn't completely grasp, with the new command dispatch mechanism
that's not the case anymore, even if I have /sbin in $PATH in the
parent shell.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Currently all the throughput tests are run for 30s.  This is reflected in
both the actual parameters given to the iperf commands, but also in the
matching sleeps in test_iperf3.

Allow this to be adjusted more easily with a new parameter to test_iperf3.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[sbrivio: Reflect new parameter in comment to test_iperf3()]
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

These two commands in the DSL to run an iperf client and server are always
used together, and some of the parameters must match between them.  The
iperf3s must also be run more or less immediately after iperf3c, since
iperf3c will run a client in the background after a sleep and requires a
server to be running before it will work.

A bunch of things can be made cleaner if we make a single DSL command that
runs both sides of the test.  For now make the combined command work
exactly like the two commands together did, warts and all.

This does lose the ability for the DSL scripts to give additional options
to the iperf3 server, but we weren't using that anyway.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>