Sometimes when under heavy load, the CI machines can take a significant
amount of time to bring up a python process (~10s). The timeouts for
the network tests were chosen without much thought, and didn't leave
much room for this sort of delay.
This patch brings up timeouts for ntetwork tests 20s -> 60s
The speed of packets on the local network exceeds even the speed of
the ethernet hardware on some of the less powerful devices. Adding
a small delay which can be expected from a real DTLS handshake prevents
this condition from occuring.
This commit reduces the thread stack from 2k to 1k for each thread in
the parallel network tests. This allows the test to run on more
constrained devices (like the LPC1768).
*_packet_pressure_parallel tests are useful for checking for synchronization
errors, but push the practical limitations of the network stack. Failing
these tests is not unreasonable.
*_packet_pressure tests are a little bit less unreasonable, but also
push the practical limitations of the network stack. Hopefully these
will become stable in the near future.
Despite being able to buffer an arbitrary stream of data,
TCP send is still limited by the available buffer space in the
network stack. Errors from TCP send are perfectly reasonable
and should be handled by reducing the buffer that is attempted.
These tests could adopt the dynamically sized buffers used for the
packet-pressure tests, however throughput is not an important feature
of these tests.
Printing out dropped packets caused significantly more overhead in the
parallel tests due to increased noise on the network. This noise would
push the tests past their provided timeouts.
Dynamic buffers gives the network stack the maximum throughput while
still supporting smaller devices. This should expose the largest number
of issues across differently sized platforms.
Additionally, restructured the UDP tests to avoid unintentionally flooding
the recieving side with bad data after failed packets.
Also, added a bit more documentation
A larger buffer gives the network stack the best options for maximizing
throughput. However, the initial buffer size did not fit on small
targets. Resized 8192 -> 1024.
Added test for the pattern of packets used during the DTLS
handshake. This pattern (5x ~300 byte packets) has been very
problematic for new network interfaces.
Attempt to maximize the devices bandwidth with an exponentially growing
transaction of random sequences. Also prints the time taken and bandwidth
reached during the tests.
Martin Kojtal
Christopher Haster
Bartek Szatkowski
Brian Daniels
Sam Grove