Data transfer time.

Hey Roy,

Thanks for the reply.

1- QOS I used:

• For "Publisher" qos I use:
• <datawriter_qos topic_filter="SequenceData_*" base_name="DataWriter_1k5"/> for 10k data size each 33ms. 
• <datawriter_qos topic_filter="ProcessedPixels30MB_*" base_name="DataWriter_30MB"/> for 30MB data size each 66 ms.
• For "Subscriber" qos I use:
• <datareader_qos topic_filter="SequenceData_*" base_name="DataReader_1k5"/> for 10k data size reception each 33ms.
• <datareader_qos topic_filter="ProcessedPixels30MB_*" base_name="DataReader_30MB"/> for 30MB data size reception each 66 ms.

2. To make measurement, I save the time at differents steps:

• Subscriber:
• As, in my code, data reception can be done through a WaitSet or a DDSDataReaderListener and DDSDomainParticipant::get_current_time() fails in case of callback call, I "get_current_time" using gettimeofday as follow:

inline DDS_Time_t getDDSTimeofday() {

static const DDS_UnsignedLong USEC_to_NANOSEC = 1000UL;

struct timeval tv;
if (gettimeofday(&tv, NULL) != 0) return DDS_TIME_ZERO;
DDS_Time_t crtTime;
crtTime.sec = tv.tv_sec;
crtTime.nanosec = tv.tv_usec * USEC_to_NANOSEC;
return crtTime;

}

• So, here after, the code in on_data_available() function where I save steps times :

void DataReader <Foo>::on_data_available(DDSDataReader* reader)
{

typename Foo::DataReader *dataReader = Foo::DataReader::narrow(reader);
if (dataReader == NULL) {

LOG_ERROR(Topic<Foo>::_topicName << ": DataReader narrow error");
return;

}
typename Foo::Seq dataSeq;
DDS_SampleInfoSeq infoSeq;
DDS_ReturnCode_t retCode = dataReader->take(dataSeq, infoSeq, DDS_LENGTH_UNLIMITED, DDS_ANY_SAMPLE_STATE, DDS_ANY_VIEW_STATE, DDS_ANY_INSTANCE_STATE);
if (retCode == DDS_RETCODE_NO_DATA) {

LOG_ERROR(Topic<Foo>::_topicName << ": dataReader->take error=" << retCode);
return;

}
else if (retCode != DDS_RETCODE_OK) {

LOG_ERROR(Topic<Foo>::_topicName << ": take error " << retCode);
return;

}

for (int i = 0; i < dataSeq.length(); ++i) {

if (_seqDataLengthMax < dataSeq.length()) {

_seqDataLengthMax = dataSeq.length();
LOG_INFO(Topic<Foo>::_topicName << ": _seqDataLengthMax=" << _seqDataLengthMax << " dataSeq.maximum=" << dataSeq.maximum());

}

if (infoSeq[i].valid_data) {

if (infoSeq[i].view_state == DDS_NEW_VIEW_STATE) {

LOG_INFO(Topic<Foo>::_topicName << ": Found new instance; _patientName = " << dataSeq[i]._patientName);

}

// Get current time
// ----------------
DDS_Time_t crtTime = getDDSTimeofday();

SavedData savedData;
savedData._cbTS = DDS_Time_t::from_nanos(dataSeq[i]._header._cbNanoSec);
savedData._wrTS = DDS_Time_t::from_nanos(dataSeq[i]._header._writeNanoSec);
savedData._txTS = infoSeq[i].source_timestamp;
savedData._rxTS = infoSeq[i].reception_timestamp;
savedData._rdTS = crtTime;
...

• For each data received I compute different delta time (based on savedData structure above). I attach to this topic one results files, with followinfg computed time meaning:
• Cb = Send Callback time (DDSDomainParticipant::get_current_time() called in Publisher side).
• Wr = After writing data (Just before FooDataWriter::write() call) (DDSDomainParticipant::get_current_time() called in Publisher side).
• Tx = DDS_SampleInfoSeq::source_timestamp => RTI middleware time
• Rx = DDS_SampleInfoSeq::reception_timestamp => RTI middleware time
• Rd = Read time (after FooDataReader::take) (see here before).

2.1: Data are sent periodically, each 33 msec for the 10kb and 66 msec for the 30 MB.

2.2: No

2.3: I'm based on C++ API.

2.4:

• I do the tests (results attached to this topic) on a HP Z820, with "Red Hat Enterprise Workstation release 6.7 (Santiago).
• Software compiled on a VMWare Helios 6.7 (Red Hat 6), with "TARGET_ARCH = x64Linux2.6gcc4.4.5" selected by rtiddsgen (gcc version: gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)).

Hope I'm clear enough.

Regards

Patrice

Hi  Roy,

Neither do I. I'm already based on "Generic.StrictReliable.LargeData.FastFlow" builtin qos.  I did some tests with differents flow_controller, but without real success.