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Brief Report on Tests Related to the e-VLBI Project

Brief Report on Tests Related to the e-VLBI Project. Richard Hughes-Jones The University of Manchester. DataGrid WP7 – Dante Tests on the G ÉANT Core End-2-End Measurements from the 4 th Year VLBI Project at Manchester DiskPack-2-Memory Throughput and PCI Activity in a Mark5 PC

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Brief Report on Tests Related to the e-VLBI Project

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  1. Brief Report on Tests Related to the e-VLBI Project Richard Hughes-Jones The University of Manchester DataGrid WP7 – Dante Tests on the GÉANT Core End-2-End Measurements from the 4th Year VLBI Project at Manchester DiskPack-2-Memory Throughput and PCI Activity in a Mark5 PC Update on 1 and 10 Gigabit Ethernet NICs in the PC JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  2. DataGrid WP7 – Dante Tests on the GÉANT Core • Set-up • Supermicro PC in: • London GEANT PoP • Amsterdam GEANT PoP • Smartbits in: • London GEANT PoP • Frankfurt GEANT PoP • Long link UK-SE-DE2-IT-CH-FR-BE-NL • Short Link UK-FR-BE-NL JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  3. Tests GÉANT Core: UDP throughput • UDP Throughput • London-Amsterdam • Available BW to packet on wire • Then 1/t • Wire rate 998 Mbit/s for packets > 1400 bytes • Packet Loss • None for large packets • Dips in BW lined to packet loss • SysKonnect NIC int. per packet • CPU load important JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  4. Tests GÉANT Core: Packet re-ordering • Effect of Packet size • London-Amsterdam • Packets at 10 µs – line speed • 10,000 sent • Packet Loss ~ 0.1% • Re-order Distribution JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  5. Tests GÉANT Core: Packet re-ordering • Effect of LBE background • Amsterdam-London • BE Test flow • Packets at 10 µs – line speed • 10,000 sent • Packet Loss ~ 0.1% • Re-order Distributions: JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  6. VLBI Project: Test Topology SURFnet Manchester JIVE Dwingaloo Jodrell SuperJANET4 Adam Mathews Steve O’Toole Univ of Manchester JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  7. VLBI Project: Throughput • Manchester to Dwingeloo • 2.0G Hz Xeon 1.2 GHz PIII • Re-ordering vs Offered Load JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  8. 1-way Delay – note the packet loss (points with 0 –way delay) VLBI Project: Jitter & 1-way Delay • 1472 byte Packets man -> JIVE • FWHM 22 µs (B2B 3 µs ) JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  9. VLBI Project: Packet Loss Distribution • Measure the time between lost packets in the time series of packets sent. • Lost 1410 in 0.6s • Is it a Poisson process? • Assume Poisson is stationary λ(t) = λ • Use Prob. Density Function:P(t) = λ e-λt • Mean λ = 2360 / s[426 µs] • Plot log: slope -0.0028expect -0.0024 • Could be additional process involved JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  10. VLBI Project: Packet Loss – Is it Poisson? • Divide time series of packets into 1000 slices of 50 packets • Total lost packets 1410 • Average number / slice = 1.4 • Calc Poisson ProbabilityP(n, µ) = µ n e -µ n! • Curves close but not exact • Could be more than 1 process JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  11. VLBI Project: Packet Loss – Long Range Effects? • Aggregated Variance Method • Divide time series length N into blocks of size m • Calc mean of each section Xm(k) k= 1 … N/m • Calc variance VXm of these Xm(k) • Vary m size of the blocks • Plot on log-log & fit slope β • Hurst parameter Hβ = 2H -2 • Measure:β = -0.355 which gives H 0.822 • H =1 no long range dependence JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  12. Traffic Flows • Manchester – NetNorthWest - SuperJANET Access links • Two 1 Gbit/s • Access links:SJ4 to GÉANT GÉANT to SurfNet JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  13. Read / Write n bytes  time Wait time Throughput & PCI transactions on the Mark5 PC: • Mark5 uses Supermicro P3TDLE • 1.2 GHz PIII • Mem bus 133/100 MHz • 2 *64bit 66 MHz PCI • 4 32bit 33 MHz PCI Ethernet NIC IDE Disc Pack SuperStor Input Card Logic Analyser Display JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  14. PCI Activity: Read 1 data block 0 wait time • Data block 131,072 bytes • Read consists of: • Setup CSRs • Data movement • Update CSRs • Data block contains PCI bursts 4096 bytes long • For 0 wait between reads: • Data block 608µs long • Then 655µs gap • PCI transfer rate 830 Mbit/s • Read_sstor rate 778 Mbit/s (97 Mbyte/s) Data Block CSR Access PCI Burst JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  15. PCI Activity: Read Multiple data blocks 0 wait • Read 999424 bytes • Each Data block: • Setup CSRs • Data movement • Update CSRs • For 0 wait between reads: • Data blocks ~600µs longtake ~6 ms • Then 744µs gap • PCI transfer rate 1188Mbit/s(148.5 Mbytes/s) • Read_sstor rate 778 Mbit/s (97 Mbyte/s) • PCI bus occupancy: 68.44% • Concern about Ethernet Traffic 64 bit 33 MHz PCI needs ~ 82% for 930 Mbit/s Expect ~360 Mbit/s JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  16. PCI Activity: Read Throughput • Flat then 1/t dependance • ~ 860 Mbit/s for Read blocks >= 262144 bytes • CPU load ~20% • Concern about CPU load needed to drive Gigabit link JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  17. 10 GigEthernet: Throughput • 1500 byte MTU gives ~ 2 Gbit/s • Used 16144 byte MTU max user length 16080 • DataTAG Supermicro PCs • Dual 2.2 GHz Xenon CPU FSB 400 MHz • PCI-X mmrbc 512 bytes • wire rate throughput of 2.9 Gbit/s • CERN OpenLab HP Itanium PCs • Dual 1.0 GHz 64 bit Itanium CPU FSB 400 MHz • PCI-X mmrbc 512 bytes • wire rate of 5.7 Gbit/s • SLAC Dell PCs giving a • Dual 3.0 GHz Xenon CPU FSB 533 MHz • PCI-X mmrbc 4096 bytes • wire rate of 5.4 Gbit/s JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  18. 10 GigEthernet: PCI-X Activity • Supermicro P4DP8-2G motherboard Packet transmission Memory to NIC CSR Access PCI-X segment 512 bytes Transfer of 16114 bytes Interrupt Packet reception NIC to Memory JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  19. 10 GigEthernet: Tuning PCI-X JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  20. 10 GigEthernet at SC2003 BW Challenge (Phoenix) • Three Server systems with 10 GigEthernet NICs • Used the DataTAG altAIMD stack 9000 byte MTU • Streams From SLAC/FNAL booth in Phoenix to: • Pal Alto PAIX • Chicago Starlight • Amsterdam SARA JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  21. JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  22. Traffic QoS Classes on GÉANT Backbone Max Throughput on 2.5 G PoS • Normal Traffic + • Radio Astronomy Data + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Less Than Best Effort • 2.0 Gbit/s • Normal Traffic + • Radio Astronomy Data • 500 Mbit/s • Normal Traffic JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

  23. Some Measurements made during ER2002 JIVE VLBI Network Meeting 28 Jan 2004 R. Hughes-Jones Manchester

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