On 26/06/2024 22:48, cjohn...@serranosystems.com wrote:
Hi,
I appreciate the response. I previously made all of those changes
(except bios, DPDK, and Sprectre). In addition, I have MTU at 9000. I
just re-verified.
I don't *think* the 2974 SOM embedded computer has the type of interface
that would be supported by DPDK, but I could
be wrong.
I’m still getting the U’s.
I think the basic problem is that 4-core i7 on that board is now a
9-year-old design, and maxes out at 2.8GHz clock
frequency, and it just doesn't have enough grunt to sustain 200e6 SPS.
I think the MTU issue is a red-herring. The packet-overhead difference
between 9000 and 8000 MTU is very small
(about 0.1% using a rough number of 40 bytes of packet overhead).
The interrupt-load difference would be
about 12.5%, except that would be a naive over-estimate given that
the 10Gig NIC subsystem almost certainly
does a lot of interrupt aggregation, etc.
So we could have the same common code as a starting point, I modified
your tx_timed_samples.cpp provided below so you can reproduce the problem.
Here are the changes:
*
Sends continuously (instead of some a set number of samples)
*
Data is sc16 and not fc32
*
Data rate is 200e6 SPS instead of a much lower value
|// // Copyright 2010-2011,2014 Ettus Research LLC // Copyright 2018
Ettus Research, a National Instruments Company // //
SPDX-License-Identifier: GPL-3.0-or-later // #include
<uhd/usrp/multi_usrp.hpp> #include <uhd/utils/safe_main.hpp> #include
<uhd/utils/thread.hpp> #include <boost/format.hpp> #include
<boost/program_options.hpp> #include <boost/thread/thread.hpp>
#include <complex> #include <iostream> namespace po =
boost::program_options; int UHD_SAFE_MAIN(int argc, char* argv[]) { //
variables to be set by po std::string args; std::string wire; double
seconds_in_future; size_t total_num_samps; double rate; float ampl; //
setup the program options po::options_description desc("Allowed
options"); // clang-format off desc.add_options() ("help", "help
message") // ("args",
po::value<std::string>(&args)->default_value(""), "single uhd device
address args") ("args",
po::value<std::string>(&args)->default_value("type=x300,addr=192.168.40.2"),
"single uhd device address args") ("wire",
po::value<std::string>(&wire)->default_value(""), "the over the wire
type, sc16, sc8, etc") ("secs",
po::value<double>(&seconds_in_future)->default_value(1.5), "number of
seconds in the future to transmit") ("nsamps",
po::value<size_t>(&total_num_samps)->default_value(10000), "total
number of samples to transmit") // ("rate",
po::value<double>(&rate)->default_value(100e6/16), "rate of outgoing
samples") ("rate", po::value<double>(&rate)->default_value(200e6),
"rate of outgoing samples") ("ampl",
po::value<float>(&l)->default_value(float(0.3)), "amplitude of each
sample") ("dilv", "specify to disable inner-loop verbose") ; //
clang-format on po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::notify(vm); // print the help message if (vm.count("help")) {
std::cout << boost::format("UHD TX Timed Samples %s") % desc <<
std::endl; return ~0; } bool verbose = vm.count("dilv") == 0; //
create a usrp device std::cout << std::endl; std::cout <<
boost::format("Creating the usrp device with: %s...") % args <<
std::endl; uhd::usrp::multi_usrp::sptr usrp =
uhd::usrp::multi_usrp::make(args); std::cout << boost::format("Using
Device: %s") % usrp->get_pp_string() << std::endl; // set the tx
sample rate std::cout << boost::format("Setting TX Rate: %f Msps...")
% (rate / 1e6) << std::endl; usrp->set_tx_rate(rate); std::cout <<
boost::format("Actual TX Rate: %f Msps...") % (usrp->get_tx_rate() /
1e6) << std::endl << std::endl; std::cout << boost::format("Setting
device timestamp to 0...") << std::endl;
usrp->set_time_now(uhd::time_spec_t(0.0)); // create a transmit
streamer // uhd::stream_args_t stream_args("fc32", wire); // complex
floats uhd::stream_args_t stream_args("sc16", "sc16");
uhd::tx_streamer::sptr tx_stream = usrp->get_tx_stream(stream_args);
// allocate buffer with data to send //
std::vector<std::complex<float>> buff(tx_stream->get_max_num_samps(),
std::complex<float>(ampl, ampl)); typedef uint16_t sample_t; // Either
the I or Q portion of an IQ sample.
std::vector<std::complex<sample_t>>
buff(tx_stream->get_max_num_samps(), std::complex<sample_t>(ampl *
32767, ampl * 32767)); // setup metadata for the first packet
uhd::tx_metadata_t md; md.start_of_burst = false; md.end_of_burst =
false; md.has_time_spec = true; md.time_spec =
uhd::time_spec_t(seconds_in_future); // the first call to send() will
block this many seconds before sending: const double timeout =
seconds_in_future + 0.1; // timeout (delay before transmit + padding)
#if 1 while (true) { size_t num_tx_samps =
tx_stream->send(&buff.front(), buff.size(), md); if (num_tx_samps <
buff.size()) { std::cerr << "Send timeout..." << std::endl; } // do
not use time spec for subsequent packets md.has_time_spec = false; }
#else size_t num_acc_samps = 0; // number of accumulated samples while
(num_acc_samps < total_num_samps) { size_t samps_to_send =
std::min(total_num_samps - num_acc_samps, buff.size()); // send a
single packet size_t num_tx_samps = tx_stream->send(&buff.front(),
samps_to_send, md, timeout); // do not use time spec for subsequent
packets md.has_time_spec = false; if (num_tx_samps < samps_to_send)
std::cerr << "Send timeout..." << std::endl; if (verbose) std::cout <<
boost::format("Sent packet: %u samples") % num_tx_samps << std::endl;
num_acc_samps += num_tx_samps; } #endif // send a mini EOB packet
md.end_of_burst = true; tx_stream->send("", 0, md); std::cout <<
std::endl << "Waiting for async burst ACK... " << std::flush;
uhd::async_metadata_t async_md; bool got_async_burst_ack = false; //
loop through all messages for the ACK packet (may have underflow
messages in queue) while (not got_async_burst_ack and
tx_stream->recv_async_msg(async_md, timeout)) { got_async_burst_ack =
(async_md.event_code == uhd::async_metadata_t::EVENT_CODE_BURST_ACK);
} std::cout << (got_async_burst_ack ? "success" : "fail") <<
std::endl; // finished std::cout << std::endl << "Done!" << std::endl
<< std::endl; return EXIT_SUCCESS; } |
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