These two values where being mixed up in the code. To summarize:
- The MTU is the max CHDR packet size, including header & timestamp.
- The max payload is the total number of bytes regular payload plus
metadata that can be fit into into a CHDR packet. It is strictly
smaller than the MTU. For example, for 64-bit CHDR widths, if
a timestamp is desired, the max payload is 16 bytes smaller than
the MTU.
The other issue was that we were using a magic constant (DEFAULT_SPP)
which was causing conflicts with MTUs and max payloads.
This constant was harmful in multiple ways:
- The explanatory comment was incorrect (it stated it would cap packets
to 1500 bytes, which it didn't)
- It imposed random, hardcoded values that interfered with an 'spp
discovery', i.e., the ability to derive a good spp value from MTUs
- The current value capped packet sizes to 8000 bytes CHDR packets, even
when we wanted to use bigger ones
This patch changes the following:
- noc_block_base now has improved docs for MTU, and additional APIs
(get_max_payload_size(), get_chdr_hdr_len()) which return the
current payload size given MTU and CHDR width, and the CHDR header
length.
- The internally used graph nodes for TX and RX streamers also get
equipped with the same new two API calls.
- The radio, siggen, and replay block all where doing different
calculations for their spp/ipp values. Now, they all use the max
payload value to calculate spp/ipp. Unit tests where adapted
accordingly. Usage of DEFAULT_SPP was removed.
- The replay block used a hardcoded 16 bytes for header lengths, which
was replaced by get_chdr_hdr_len()
- The TX and RX streamers where discarding the MTU value and using the
max payload size as the MTU, which then propagated throughout the
graph. Now, both values are stored and can be used where appropriate.
The checks from the new clang-tidy file are applied to the source tree
using:
$ find . -name "*.cpp" | sort -u | xargs \
--max-procs 8 --max-args 1 clang-tidy --format-style=file \
--fix -p /path/to/compile_commands.json
This removes the following Boost constructs:
- boost::shared_ptr, boost::weak_ptr
- boost::enable_shared_from_this
- boost::static_pointer_cast, boost::dynamic_pointer_cast
The appropriate includes were also removed. All C++11 versions of these
require #include <memory>.
Note that the stdlib and Boost versions have the exact same syntax, they
only differ in the namespace (boost vs. std). The modifications were all
done using sed, with the exception of boost::scoped_ptr, which was
replaced by std::unique_ptr.
References to boost::smart_ptr were also removed.
boost::intrusive_ptr is not removed in this commit, since it does not
have a 1:1 mapping to a C++11 construct.
transports:
Transports build on I/O service and implements flow control and
sequence number checking.
The rx streamer subclass extends the streamer implementation to connect
it to the rfnoc graph. It receives configuration values from property
propagation and configures the streamer accordingly. It also implements
the issue_stream_cmd rx_streamer API method.
Add implementation of rx streamer creation and method to connect it to
an rfnoc block.
rfnoc_graph: Cache more connection info, clarify contract
Summary of changes:
- rfnoc_graph stores more information about static connections at the
beginning. Some search algorithms are replaced by simpler lookups.
- The contract for connect() was clarified. It is required to call
connect, even for static connections.
