1. Yunhong Gu & Robert Grossman University of Illinois at Chicago
UDT Tutorial
Yunhong Gu & Robert Grossman
University of Illinois at Chicago

2. Outline Introduction Installation Programming using UDT
Performance tuning
Conclusion

3. Introduction UDT – UDP-based Data Transfer Application level
End-to-end
Bi-directional
For shared networks
But can be tuned for private networks
C++ library

4. UDT History 2000: SABUL Concept 2001: SABUL version 1.0 2002: dSABUL

5. Project Online sf.net/projects/udt
Source code, documentations, mailing lists, bug reports
Tarball release and CVS

6. Installation Make the C++ source code Tested support hardware
IA32, IA64, AMD64, Power PC, SPARC
Tested support OS
Linux, OS X, Windows, UNIX
make -e arch=XXX os=YYY

7. Post-Installation LD_LIBRARY_PATH
Testing using appserver and appclient
./appserver [port]
./appclient <server-addr> <server-port>

8. Programming using UDT socket-like API UDT:: namespace qualifier
UDTERROR

9. Programming using UDT int client = socket(AF_INET, SOCK_STREAM, 0);
connect(client, (sockaddr*)&serv_addr, sizeof(serv_addr));
If (-1 == send(client, data, size, 0)) {
//error processing }
UDTSOCKET client = UDT::socket(AF_INET, SOCK_STREAM, 0);
UDT::connect(client, (sockaddr*)&serv_addr, sizeof(serv_addr));
If (UDTERROR == UDT::send(client, data, size, 0)) {
//error processing }

10. Configuration
setsockopt/getsockopt

11. Overlapped IO
int send(   UDTSOCKET,              const char *buf,    int len,   int flags, 
int *handle = NULL, 
UDT_MEM_ROUTINE routine = NULL );
void (UDT_MEME_ROUTINE*)(char*, int);

12. Overlapped IO
bool getoverlappedresult(   UDTSOCKET u,   const int& handle,   int& progress,   const bool& wait );

13. Overlapped IO New Data User Buffer Data Protocol Buffer

14. Performance monitoring
Monitor UDT performance statistics
Monitor internal UDT parameters
Diagnose network and application configurations
int perfmon(
UDTSOCKET u,
TRACEINFO* perf );

15. Performance monitoring
TRACEINFO structure
Aggregate information
Timestamp, Total send/recv/retrans/loss, etc.
Local information (values since last time perfmon was called)
Local send/recv/retrans/loss, send/recv rate
Instant value
RTT, cwnd, ipt, etc.

16. Performance Tuning UDT buffer size UDP buffer size IO block size
Larger is better
UDP buffer size
SNDBUF << RCVBUF
Larger is NOT better
IO block size
Larger is better, but better less than the UDT buffer size
File IO block size: mystery

17. Thank you!