UDT Tutorial

1
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
• 2002 SABUL version 2.0, 2.1, 2.2, 2.3,
• 2003 UDT 1.0
• 2004 UDT 1.1 1.2
• 2004 UDT 2.0
• 2005 UDT 3.0

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 archXXX osYYY

7
Post-Installation

• LD_LIBRARY_PATH
• Testing using appserver and appclient
• ./appserver port
• ./appclient ltserver-addrgt ltserver-portgt

8
Programming using UDT

• socket-like API
• UDT namespace qualifier
• UDTSOCKET
• 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 UDTsocket(AF_INET,
SOCK_STREAM, 0) UDTconnect(client,
(sockaddr)serv_addr, sizeof(serv_addr)) If
(UDTERROR UDTsend(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
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
• Larger is better
• UDP buffer size
• SNDBUF ltlt 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!