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    Developer's meeting

    → Europe/Zurich
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    Present: Giovanna, Roland, Enrico, Thijs, Milo, Eric, Phil, Frank

    Re-ordering / compression (see Milo's slides):

    • metadata indicating format: 8 bits available for bot re-ordering and compression, so can accommodate format "evolution"
    • now also compressing header information, while still storing full frame header in case of any error
    • QAT performance results obtained on np04-srv-017, still using PCIe card
      • algorithm for on-board QAT is identical so expect same compression factor (but improved speed)
    • factor >~ 3.5: this is assuming that header compression is not very effective (so somewhat pessimistic)
      • suspect that still lower factor than for RCE is due to the use of a generic rather than a custom algorithm (in s/w can also achieve a factor between 5 and 7)
    • root issue with results (compression factor down to ~ 2.5) observed last week: bug in QATzip resulting in use (always) of static rather than dynamic Huffman table
      • bug has been fixed in updated QATzip
    • Roland: can now run with 5 inputs at up to 70 Hz (limit seems compatible with 3 ms/event * 70 events / ( link * s) * 5 links = 1.05 ~ 1)
    • Eric will read the note to see if there is any information that is still needed for uBooNE

    Software & firmware (Enrico):

    • s/w: Roland & Joern solved issue preventing two NIC interfaces from being usable by different CPUs (newer libfabric version)
    • f/w:
      • initialisation instabilities fixed (thanks to Andrea, Frans, Henk, Rene)
      • presently attempting to see if making the "last" FIFO deeper helps mitigate hiccups due to PCIe unavailability
    • new FELIX host will not arrive before mid October (lack of computer memory @vendor) (!)
      • so may need to stay with two FELIX hosts for the time being (backpressure turns out to be related to the limited number of available cores)
      • some improvement perhaps possible now that NIC issue is solved (idea: use 2 CPUs w/ 5 links / CPU)

    Next meeting: tentatively on September 19

    There are minutes attached to this event. Show them.
      • 17:00 → 17:20
        Reordering and QAT integration in the BoardReader 20m
        Speakers: Mr Milo Vermeulen (Nikhef National institute for subatomic physics (NL)), Roland Sipos (CERN), Thijs Miedema
        FELIXwork20180905.pdf