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GTT status

GTT status. Items reviewed: Results of GTT tests with 3 MVD-ADC crates. Aims Hardware and software setup used Credit control implementation Latency and rate results - test 1 Latency and rate results - test 2 System acceptability GTT time schedule and requirements on ZEUS DAQ.

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GTT status

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  1. GTT status • Items reviewed: • Results of GTT tests with 3 MVD-ADC crates. • Aims • Hardware and software setup used • Credit control implementation • Latency and rate results - test 1 • Latency and rate results - test 2 • System acceptability • GTT time schedule and requirements on ZEUS DAQ. A.Polini and C.Youngman

  2. Results of tests with 3 MVD-ADC crates • Aims • Implement the credit controlled GTT described in ZEUS Note 99-74 with data input from 3 MVD-ADC crates. • Measure latency and rate characteristics in the absence of algorithm data processing in week available. • Make a statement about the acceptability of the system w.r.t. the ZEUS DAQ. • Hardware and software setup used • parts of the MVD test system as of 23/3/01 • 3 complete and fully debugged ADC/readout crates. • Clock&Control system incl. Pulse generator ext. trigger. • 7 Dual 1GHz Intel PCs • 1 Intel 12 port giga/fast ethernet switch. • PPC VME (fast) and PC(giga) CPUs connected to separate ports • MVD run control and monitoring software. A.Polini and C.Youngman

  3. GTT credit control implementation • keypoints • code derived from a non hardware simulation • allows RC configurations to be tested • allows message and IP connectivity to be debugged • uses a common function library for buffering • ordering of events with GFLT# before sending to GSLT/EVB • gathering complete events at GTT and EVB • network messages sent consists of: • an short control message (<128B) in XDR tagged union. • endian independent • contents (GFLT#,etc.) remove the need to look into the data • and, optionally, a data message. • all programs are currently single threaded. A.Polini and C.Youngman

  4. GFLT ACCEPT 3 1 1 1 8 6 1 2 3 4 2 1 7 5 1 2 1 1 2 0/6 4 GSLT EVB GSLT DECISION GTT process, network and trigger connections - credit based. CTD-SLT STT-SLT MVD-ADC 2 4 2 1 2 2 1 2 1 2 3 GTT 3 TOEVB TOGSLT FROMGSLT A.Polini and C.Youngman

  5. Control message definitions • Credit • 0. credit number allocation (SETUP) • 1. credit/socket resolution (SETUP) • 2. credit list (SETUP) and credit notification (ACTIVE) • Trigger • 3. SLT data to GTT (ACTIVE) • 4. GTT end algorithm credit notification (ACTIVE) • 5. GTT algorithm result to GSLT (ACTIVE) • 6. GSLT decision to MVD and specific GTT (ACTIVE) • EVB • 7. GTT result and MVD cluster data (ACTIVE) • 8. MVD strip data (ACTIVE) A.Polini and C.Youngman

  6. GTT hardware realization GFLT ACCEPT 3 1 1 1 8 6 1 2 3 4 2 1 7 5 1 2 1 1 2 0/6 4 EVB GSLT GSLT DECISION CTD-SLT STT-SLT MVD-ADC 2 4 2 1 2 2 1 2 1 2 3 GTT 3 TOEVB TOGSLT FROMGSLT A.Polini and C.Youngman

  7. Latency and rate results - test 1 • Fix SLT & EVB data size/crate and vary N GTT • measurement parameters • SLT size/crate 2.6, 2.7 and 1.9 kB • EVB size/crate 4.6, 4.6 and 3.3 kB • vary N GTT through: 1,2,4,8,12,18,24 and 30 (ie. 5/PC). • Pulse generator rate 600 Hz. • GSLT accept prescale factor 10 • results are independent of N GTT • Sustained rate 500 Hz mean with 60 Hz p2p fluctuation. • Latency at TOGSLT 1.7ms with low level but long tail. • Latency at TOEVB 2.9ms - did not look at tail. • conclusions • credit turn round of 1.7 ms • message transit time ~0.9ms (cf. Table 4 TCP PPC->PC performance tests = 3/4245 + 2/12306) • N GTT independence surprising especially for 1 GTT, understood ? • rate and fluctuation not understood, credit bursting ?. • latency tails not understood, more detailed tests required. A.Polini and C.Youngman

  8. GTT latency at TOGSLT A.Polini and C.Youngman

  9. Fix N GTT and vary SLT & EVB data size/crate measurement parameters pulse generator rate600 Hz GSLT accept prescale factor 10 N GTT fixed at 6, ie. 1/PC results Latency and rate results - test 2 • conclusions • bigger SLT/EVB data sizes have lower rates and higher latencies ! • too early to say how stable the measured values are. A.Polini and C.Youngman

  10. Acceptability of GTT performance • Non algorithm processing results • 3 MVD-ADC crate system • the measured rates (>500Hz) for SLT and EVB data sizes of <2.5kB/crate and <4.5kB/crate are close to the ZEUS DAQ requirement of ~550Hz. • the measured SLT and EVB latencies appear to be stable and acceptable if the tails can be understood and reduced further. • CTD-SLT connection • The measured latency of the CTD-SLT at the GSLT was measured in the ZEUS DAQ system in 1999. • The CTD-SLT data is available a few ms after the GFLT accept thus network contention at the GTT is not anticipated. • Conclusions • The measurements indicate that the GTT will work. A.Polini and C.Youngman

  11. Time schedule and ZEUS DAQ requirements • MVD related • week 17 (23/4) ? GFLT trigger interface to C&C • EVB related • week 18 (30/4) ? tests of PC/PCI-TP interface needed for • sending SLT result • receiving GSLT decision • week 19 (7/5) ? tests of MVD event building via ethernet • by week 19 (7/5) DDL definitions of data banks • GSLT related • by week 19 (7/5) definition of GTT decision • week 19 (7/5) ? tests GSLT connection • DAQ chain • week 20 (14/5) and thereafter tests with full DAQ system including the new EVB subsystems. A.Polini and C.Youngman

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