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vlbi_udp Throughput Performance and Stability.

vlbi_udp Throughput Performance and Stability. Richard Hughes-Jones The University of Manchester www.hep.man.ac.uk/~rich/ then “Talks”. Ring buffer. vlbi_udp Flow Diagram. Vlbi_control. vlbi_send. vlbi_recv. Control thread. Control thread. TCP Control. Disk. Memory. Disk. Memory.

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vlbi_udp Throughput Performance and Stability.

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  1. vlbi_udpThroughput Performance and Stability. Richard Hughes-Jones The University of Manchesterwww.hep.man.ac.uk/~rich/ then “Talks” ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  2. Ring buffer vlbi_udp Flow Diagram Vlbi_control vlbi_send vlbi_recv Control thread Control thread TCP Control Disk Memory Disk Memory Input thread Output thread Ring buffer UDP Data Send thread Receive thread From Simon Casey ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  3. History or the story so far: • iGrid2002 monolithic code • Convert to use pthreads • control • Data input • Data output • Code branch for Simon’s file transfer tests • Work on vlbi_recv: • Output thread polled for data in the ring buffer – burned CPU • Input thread signals output thread when there is work to do – else wait on semaphore – packet loss at high rate, variable thoughput • Output thread uses sched_yield() when no work to do – CPU used • Network performance – in progress ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  4. Instability: 2 streams into JIVE, March 2006 From Simon Casey ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  5. Early B2B UDP Tests • Kernel 2.6.6 (May06) • vlbi_recv semaphore • Wait 15 us; signal 200 events • Unstable throughput • ~815 Mbit/s • Packet loss ~ 0.05% • Lost at top of IP stack • Inter-packet time • Processing time • mean 0.1166 sigma 0.3493 • CPU load: L1 ; 0; 0; 0; 100; 0; 0; 0;; L2 ; 0; 0; 0; 99; 0; 0; 0;; L3 ; 0; 0; 0; 99; 0; 0; 0;; L4 ; 2; 0; 43; 53; 0; 1; 18 ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  6. Confirm with B2B UDP Tests • Kernel 2.6.6 (Aug06) • vlbi_recv semaphore • Wait 15 us; signal 100 events • Throughput a bit unstable • ~815 Mbit/s • Packet loss ~ 0.05% • Lost at top of IP stack • CPU number & % packet loss • Have loss when using same CPU as that servicing interrupts • Confirmed by many udpmon tests ! ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  7. B2B UDP Tests – different kernel • Kernel 2.6.9 • vlbi_recv semaphore • Wait 12 us; signal 200 events • Stable throughput • 999 Mbit/s variation less than 1 Mbit/s • No packet loss • Inter-packet time • Processing time • mean 0.1206 sigma 0.3274 • CPU load: Cpu0 : 0.0% us, 0.0% sy, 0.0% ni, 99.3% id, 0.3% wa, 0.3% hi, 0.0% si Cpu1 : 0.3% us, 0.0% sy, 0.0% ni, 99.3% id, 0.3% wa, 0.0% hi, 0.0% si Cpu2 : 0.3% us, 0.0% sy, 0.0% ni, 99.7% id, 0.0% wa, 0.0% hi, 0.0% si Cpu3 : 6.0% us, 17.0% sy, 0.0% ni, 40.3% id, 0.0% wa, 1.0% hi, 35.7% si ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  8. B2B UDP Tests • Kernel 2.6.9 • vlbi_recv sched_yield() • Wait 20 us • Stable throughput • 612.5 Mbit/s variation less than 1 Mbit/s • No packet loss • Inter-packet time • Processing time • mean 0.1005 sigma 0.1438 • CPU load: • Cpu0 : 3.7% us, 8.0% sy, 0.0% ni, 88.4% id, 0.0% wa, 0.0% hi, 0.0% si • Cpu1 : 1.0% us, 4.0% sy, 0.0% ni, 95.0% id, 0.0% wa, 0.0% hi, 0.0% si • Cpu2 : 0.0% us, 0.0% sy, 0.0% ni, 100.0% id, 0.0% wa, 0.0% hi, 0.0% si • Cpu3 : 11.6% us, 22.9% sy, 0.0% ni, 41.9% id, 0.0% wa, 1.0% hi, 22.6% si ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  9. B2B UDP Tests • Kernel 2.6.9 • vlbi_recv sched_yield() • Wait 12 us • Stable throughput • 999 Mbit/s variation less than 1 Mbit/s • No packet loss • Inter-packet time • Processing time • mean 0.1005 sigma 0.1438 • CPU load: • Cpu0 : 0.0% us, 0.0% sy, 0.0% ni, 99.7% id, 0.3% wa, 0.0% hi, 0.0% si • Cpu1 : 11.3% us, 88.7% sy, 0.0% ni, 0.0% id, 0.0% wa, 0.0% hi, 0.0% si • Cpu2 : 0.3% us, 0.0% sy, 0.0% ni, 99.3% id, 0.3% wa, 0.0% hi, 0.0% si • Cpu3 : 9.3% us, 15.6% sy, 0.0% ni, 37.5% id, 0.0% wa, 1.3% hi, 36.2% si ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  10. Next Steps • Fix the timing precision – again! • Test with latest 2.6.16 and 2.6.17 kernels • Why does shed_yield() take more CPU time? Is it a problem or not? • Test on long-distance Networks • Production (packet switched) • UKLight • Test at 4-8 Gbit ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  11. Any Questions? ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  12. More Information Some URLs 1 • UKLight web site: http://www.uklight.ac.uk • MB-NG project web site:http://www.mb-ng.net/ • DataTAG project web site: http://www.datatag.org/ • UDPmon / TCPmon kit + writeup: http://www.hep.man.ac.uk/~rich/net • Motherboard and NIC Tests: http://www.hep.man.ac.uk/~rich/net/nic/GigEth_tests_Boston.ppt& http://datatag.web.cern.ch/datatag/pfldnet2003/ “Performance of 1 and 10 Gigabit Ethernet Cards with Server Quality Motherboards” FGCS Special issue 2004 http:// www.hep.man.ac.uk/~rich/ • TCP tuning information may be found at:http://www.ncne.nlanr.net/documentation/faq/performance.html& http://www.psc.edu/networking/perf_tune.html • TCP stack comparisons:“Evaluation of Advanced TCP Stacks on Fast Long-Distance Production Networks” Journal of Grid Computing 2004 • PFLDnet http://www.ens-lyon.fr/LIP/RESO/pfldnet2005/ • Dante PERT http://www.geant2.net/server/show/nav.00d00h002 ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  13. More Information Some URLs 2 • Lectures, tutorials etc. on TCP/IP: • www.nv.cc.va.us/home/joney/tcp_ip.htm • www.cs.pdx.edu/~jrb/tcpip.lectures.html • www.raleigh.ibm.com/cgi-bin/bookmgr/BOOKS/EZ306200/CCONTENTS • www.cisco.com/univercd/cc/td/doc/product/iaabu/centri4/user/scf4ap1.htm • www.cis.ohio-state.edu/htbin/rfc/rfc1180.html • www.jbmelectronics.com/tcp.htm • Encylopaedia • http://www.freesoft.org/CIE/index.htm • TCP/IP Resources • www.private.org.il/tcpip_rl.html • Understanding IP addresses • http://www.3com.com/solutions/en_US/ncs/501302.html • Configuring TCP (RFC 1122) • ftp://nic.merit.edu/internet/documents/rfc/rfc1122.txt • Assigned protocols, ports etc (RFC 1010) • http://www.es.net/pub/rfcs/rfc1010.txt & /etc/protocols ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  14. Backup Slides ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  15. VLBI Network Topology ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

  16. Geant2 Launch event, June 2005 ESLEA VLBI Bits&Bytes Workshop , 31 Aug 2006, R. Hughes-Jones Manchester

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